Because the isAccessibleByUser method can be run in contexts where $INFO
is not available, an explicit check is needed.

Otherwise it's a bit ahrd to decide if access should be granted ;-)

This adds a new method that capsulates the access check that has to be
done to decide if an admin plugin's page should be shown to the user.
The default implementation is the same as before, relying only on the
forAdminOnly() method and the users' isadmin or ismanager status.

Admin plugins themselves can override the method to do additional
checks. In this patch, I added that to the usermanager plugin which will
only return true if the current auth backend can list users.

However the real idea behind this change is that the new method emits a
new event called ADMINPLUGIN_ACCESS_CHECK which would allow plugins to
overwrite it. This way it could be possible to give certain user groups
access to certain admin plugins without giving them admin or manager
permissions.

Note: this does not change how the "Admin" link is shown, it still
depends on ismanager or isadmin. A plugin as mentioned above would need
to influence the display via the MENU_ITEMS_ASSEMBLY event.

Note: this only covers the basic access check. Admin plugins may need
further adjustments for access to other parts of the plugin (like AJAX
components). An additional commit will update this for the bundled
plugins.

more complex material design icons can be somewhat larger than 1kb

This introduces an embedSVG() function that can be used at other places.

Squashed commit of the following:

commit 86183b66c5b53b47e5ddb1e0d1c155c06c331d35
Merge: ebfb1ab1 4a8f4288e
Author: Andreas Gohr <andi@splitbrain.org>
Date:   Sat Jan 21 11:20:32 2017 +0100

    Merge branch 'master' of git://github.com/ThisNameIsNotAllowed/dokuwiki into pull-request-1767

    * 'master' of git://github.com/ThisNameIsNotAllowed/dokuwiki:
      Update admin.php
      Update admin.php
      Update _admin.css
      Update admin.php
      Update html.php
      Update _admin.css
      Update html.php
      Update html.php
      Update html.php
      Update.html
      Update html.php
      Update admin.php

commit 4a8f4288e61d48156bf9c4a7c49756912e4dac25
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Fri Jan 20 09:25:52 2017 +0100

    Update admin.php

    Changed the code to check for icons being SVG files.
    This should fix php5.3 errors for using method returns straight on.

commit e43b6cae1e12c1d24efae301e6b25f79a660f353
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Fri Jan 20 08:22:41 2017 +0100

    Update admin.php

    Removed elements that could lead to behaviors that shouldn't occure.

commit 9af82fb6f43a5ce10ba9b54f1d5f5cac644c7611
Merge: b99c67797 0b8d1871c
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Thu Jan 19 16:22:02 2017 +0100

    Merge pull request #1 from ThisNameIsNotAllowed/add-c

    Added css, forced the author to use ".svg"-files for plugin icons.

commit 0b8d1871c8bd0a02aca3ff56128465e8739c96ea
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Thu Jan 19 16:17:34 2017 +0100

    Update _admin.css

    fixed some aligning for plugin names.

commit 9158649de99867574471a2b894f8611bb99b9a7f
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Thu Jan 19 15:49:20 2017 +0100

    Update admin.php

    Added method to return menu icons only in case their mime type matches svg files.

    Added warning to getMenuIcon comments telling the user to provide svg only.

commit 6df4e0f41880d40f0e7b1882d26fc647d6d2188e
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Thu Jan 19 15:46:17 2017 +0100

    Update html.php

    Added code to accept svg files only.
    Also changed names of css classes to suit dokuwiki style.

commit 3435abc52ac1dbd4e0cea291a8b30bef722638a6
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Thu Jan 19 15:41:06 2017 +0100

    Update _admin.css

    Added css for displaying plugin icons.

commit b99c67797eafdb73351f62d2db4c206426b9f828
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Thu Nov 24 14:16:23 2016 +0100

    Update html.php

    Changed the list of admin plugins.

    The icons and plugin names appearance can now be influenced by css.

commit 479c6517ff6fc6010c24b2a285249f3600bc3248
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Thu Nov 24 13:45:08 2016 +0100

    Update html.php

    Cleaned, due to too much duplicated code.

commit e621fd9788c064cc22385cfa4999a9be588bedc2
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Wed Nov 23 16:26:14 2016 +0100

    Update html.php

    Changed class name for images shown before plugin names.

commit 9099dac8483fc1aa5a875755ba3dea6e7eb3f280
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Wed Nov 23 16:24:01 2016 +0100

    Update.html

    Added icon to plugin array

commit faea3ceb7986ecd6d6bad3d8055a388f3810c4b1
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Wed Nov 23 15:56:40 2016 +0100

    Update html.php

    Added support to display plugin icons in admin menu.

commit 539e60be075ab060d7d57beadc74d94606262a2e
Author: ThisNameIsNotAllowed <ThisNameIsNotAllowed@users.noreply.github.com>
Date:   Wed Nov 23 15:51:39 2016 +0100

    Update admin.php

    Add support for icons in admin menu.

As of VIM 7.3 it is no longer possible to specify the encoding in the
modeline. This gives an error message whenever such a file is opened,
thus this commit removes the enc setting from the modeline.

This patch moved the place where DOKU_PLUGIN is defined. It no longer
can be set from a normal config (only via preload)

This patch introduces a tpl_toc() function which can be used to freely place
the Table of Contents in a template. When used, tpl_content should be called
with a parameter of false to supress the automatic TOC placement.

Note: if tpl_toc() us run *before* tpl_content(), TOCs will not work in the
preview. A work around is to run tpl_content() in a output buffer first.

This patch also adds a getTOC() function for admin plugins which allows plugin
authors to put create their own TOC which will be placed correctly in the
template. A convenience function html_mktocitem() is available.

The config manager was adjusted to make ue of this new feature, but some bugs
might remain.

darcs-hash:20070805132405-7ad00-77d2c3cdf66cc62b2d408cc6580f938636a109af.gz

darcs-hash:20070119233350-7ad00-a8ae733093693a55c2566f5ee698a7b4aa3a833a.gz

This patch adds support for a manager option as suggested in
http://www.freelists.org/archives/dokuwiki/11-2006/msg00314.html

darcs-hash:20061203134104-7ad00-72ff6422bbb4f79be325c7e77255e1eee32d0f6b.gz

This patch adds events and a third plugin type, "action" plugins, to DokuWiki.

The patch doesn't include any event signalling, that will be added in later patches.

Action plugins are loaded before most Dokuwiki processing takes place and at the
same time are given the opportunity to register handlers (or hooks) to receive
specific dokuwiki events.

Other parts of Dokuwiki (e.g. templates and syntax plugins) can also register
handlers to receive events.

Any part of Dokuwiki can create and signal events, including templates and plugins.

This patch also revises the admin plugin class by making it an extension of a
new class, DokuWiki_Plugin. The DokuWiki_Plugin_Action class also extends this
new class.

Further details of events, their signalling and handling, and of action plugins will
be added to wiki.splitbrain.org in due course :-)

darcs-hash:20060414193737-9b6ab-f23d3d9b93e4c50a3ad97ced03eabc6c0363650b.gz

Update default plugins to ensure they exit immediately
if not called from within Dokuwiki

darcs-hash:20060409233841-9b6ab-555e4fced756849a5d7b9de6e4aaaea24c6da3ae.gz

darcs-hash:20060326122952-9b6ab-f6aef3c5b2f9e936d2f32ed148d19bbd8a9da2da.gz

darcs-hash:20060322110832-283c4-d8e56c241f8a34827f1c188c4db7162ef658e010.gz

darcs-hash:20060128011605-9b6ab-38b917f8e1b311ff319d1cfd356369e428e95c3e.gz

update admin plugin base class, remove plugin_ prefix from main methods, leaving original functions in deprecated form. provide plugin name if no menutext is found

darcs-hash:20050908000305-50fdc-0d5fe129ac9ab6a39e2e0ae28b5dbcce83faa70a.gz

darcs-hash:20050904203437-7ad00-e0856739efaff3eb63b6ef0821ac318b4f84af9e.gz

darcs-hash:20050902203054-7ad00-76384ca4515031c63766eb2e54f3fd3c88ae08b9.gz

darcs-hash:20050902150527-283c4-dae58038c70aacb000f535e8173fa263ba774f52.gz

tidy up plugin manager code (rename some classes that were using admin_plugin_* format). Fix for ->setupLocale.

darcs-hash:20050829082736-50fdc-e5eff45e1d3c45bd4f23cfa468aec2a271c8fd44.gz

darcs-hash:20050824224718-50fdc-6d27ff70e60e6fe547aff6c2b305507c4ab3f669.gz