FS#2767, fix for missing security token

ensure security token is included in media url when resize parameter is passed in string form, e.g. 'w=80'

The code that is removed in this commit has either never been used
(listIndexLenghts) or was completely broken (cacheIndexDir) and was
introduced in the indexer rewrite in 2010. The idea of the rewrite was
to update the readdir cache after every index change instead of on demand.
What the code actually did was removing every updated index from the
cache as it used a wrong if condition. Simply fixing the condition
wouldn't fix the problem as then only updated indexes would be added to
the cache and furthermore the rewrite simply ignored the readdircache
setting. For now the safest solution seems to be removing the code. It
could be added again in a changed form in a future version.

The suffix parameter is only for the word length in the word index and
not for the metadata index.

When pages contain non-UTF8 chars (eg. when posted through a script or
when edited on the filesystem, parts of DokuWiki can break resulting in
missing page content. This fixes these problems by forcing the content
to UTF-8 on load. This will result in bad characters for input that is
not latin1 but contents will at least be visible.

thanks @Klap-in

adLDAP renamed the ad_username and ad_password to admin_username
admin_password recently. this makes our backend recognize the old
settings

fix ids in de lang of authAD

Fix double encoding of html diff output in syndicated feeds and subscrition emails

de/de-informal language updates for several components.

Rename ad_usernamepassword to admin_username/password

again)

canDo getUsers to false when unavailable

This reverts commit ba09710a.

Conflicts:
	lib/plugins/authad/lang/de/settings.php

Correctly identify AD account

server side resizing now needs a security hash which we can' provide in
the installer, yet.