previously it never returned any users

As suggested by @selfthinker

In Novell eDir the group search returns strings, not arrays. Added if-statement which determines if the result is an array or an string.

fix bug that only allows admins any AJAX calls

our translation interface used to submit empty files for a while but no
longer does, so these can go

The filename found in the URL will be used for old plugins missing a
base entry in their plugin.info.txt and lacking a subdirectory inside
the archive as well. This patch makes sure possible query strings aren't
included in the filename.

Note: io_download() will also try to get a filename from any
content-disposition header.

If no filename can be found we simply use an md5 sum of the URL and hope
the plugin will contain it's own hint for naming.

PHP_EOL is platform dependent, so you get in trouble while migrating
between platforms.

they were just catching and rethrowing

This reads some duplication in the from of haveing a Doku_Parser_Mode
and Doku_Parser_Mode_Plugin class which are basically the same but only
the latter extends DokuWiki_Plugin. This avoids the performance/RAM
problems mentioned in my previous commit. An interface keeps both
logically together.

With PHP 5.4 further deduplication could be done via Traits.

This makes Doku_Parser_Mode inherit from DokuWiki_Plugin which allows
for the removal of a bunch of duplicate code form
DokuWiki_Syntax_Plugin. This makes the code easier to maintain and makes
sure all DokuWiki plugins are actual instances of DokuWiki_Plugin.

However this adds a bunch of functions to the "normal" parser modes that
don't need them which could have performance/RAM implications.

this is not a extension specific cache but a global one. no need to
purge for each installed extension