fixed performance issues with gradient in Firefox (which also added gradient support for IE9) (FS#2447)

* removed all occurrences of '-moz-linear-gradient'
* added SVG as fallback for Firefox, IE9 and other browsers to page background and buttons

This time PHP and libGD is used so it should work on Windows as well.
The image quality is much better this time and the active highlight
color is read directly from the template's style.ini

This makes it easier to modify or extend the icons in the sprite.
Just place the source files in the pagetools directory and run the build
script.

as discussed at https://github.com/splitbrain/dokuwiki/pull/82#r419699

This way there's less custom code for the footer buttons needed

Add rtl.css as *screen* style, but append all RTL styles with [dir=rtl].
That has the advantage that all styles are in the same CSS output, so there are no different requests.

Later on all styles in rtl.css should be moved to their respective "parent" css file.

made styles for .pad and .site divs more specific to avoid interfering with the same classes somewhere else within the page

* localtemplate/initial_commit_from_starter: (159 commits)
  moved files to template hierarchy for merging with core
  deleted obsolete files
  added styles for screen resolutions between 480 and 768px (#26)
  minor improvements
  improved minor edits in recent changes
  increased site width a bit (#45)
  fixed search input issue caused by previous commit
  improved search box and action dropdown spacing in mobile view
  made large tables scrollable (fixes #40)
  typo
  added includes for sidebar header and footer (closes #41) and moved page header and footer inside .page div
  toned down active colour of pagetools a bit (#22)
  changed link colours (#22)
  removed outline from links (focus and active states are set differently anyway)
  added license for pagetool icons
  remove bold from link to current page inside the main content (closes #31)
  removed needless relative position on content (fixes #35)
  initialize variable
  first attempt to fix media queries on modern smartphones
  fixed logo size setting. closes #36
  ...

Conflicts:
	README
	css/_admin.css
	css/_diff.css
	css/_edit.css
	css/_footnotes.css
	css/_forms.css
	css/_imgdetail.css
	css/_links.css
	css/_modal.css
	css/_recent.css
	css/_search.css
	css/_toc.css
	css/basic.css
	css/content.css
	css/design.css
	css/includes.css
	css/print.css
	css/rtl.css
	css/structure.css
	detail.php
	images/bullet.png
	images/closed.png
	images/favicon.ico
	images/link_icon.gif
	images/mail_icon.gif
	images/open.png
	images/windows.gif
	main.php
	mediamanager.php
	style.ini
	tpl_functions.php