Added diff navigation
 Navigation links to move to previous edit before revision in left column or next/last edit after revision in right column.
Add working EoF and BoF checks when chunck reading.
Also isset on meta-last_change-date entry.
Add some breaks to while loops.
some refactoring
merge master in branch
Extension manager: First draft of the extension class
Extension manager: implemented more extension info and basic repository access
Merge branch 'master' into extension_manager
Extension manager: add language file and simple admin component
Extension manager: fix install dir for templates
Extension manager: Use getInfo() when no info.txt is available
Extension manager: Improve update check
Extension manager: implement uninstall, canModify and install/update
added basic suport for embedding (html5) videos
Extension manager: Implement extension table

This uses a lot of code and the whole design from the previous extension
manager implementation.
Add several alternative formats to video for better browser compatibility

All .webm, .ogv and .mp4 files with the same filename are automatically
chosen as alternative sources when only one of them is mentioned in the
media syntax.
added poster attribute to video if jpg or png with same file name exists
improved code for videos (restrict to 3 mimetypes, removed codec info from type attribute)
added support for html5 audio

Similar to videos, all .ogg, .mp3 and .wav files with the same filename are automatically chosen as alternative sources when only one of them is mentioned in the media syntax.
Merge branch 'extension_manager' of github.com:splitbrain/dokuwiki into extension_manager

* 'extension_manager' of github.com:splitbrain/dokuwiki:
  Extension manager: Implement extension table
  Extension manager: implement uninstall, canModify and install/update
  Extension manager: Improve update check
  Extension manager: Use getInfo() when no info.txt is available
  Extension manager: fix install dir for templates
  Extension manager: add language file and simple admin component
  Extension manager: implemented more extension info and basic repository access
  Extension manager: First draft of the extension class