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
added basic suport for embedding (html5) videos
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.
fixed typo
refactored audio/video code, removed wrong link around audio
added spacing below video and audio elements

Note: The spacing will now show as too much as long as the paragraph bug
is not fixed
Merge remote-tracking branch 'origin/master' into video-audio
Wrap thead around 1st row, when 1st cell at 1st row is tableheader. Implements FS#1764
add <THEAD> to top rows of tables when all cells are <TH>
update tests for use with <THEAD> changes
swap order ot test parameters to match expected,actual as per documentation & test output
Merge pull request #390 from splitbrain/tablethead_chris

multi-row THEAD & tests
Merge remote-tracking branch 'origin/master' into video-audio

Conflicts:
	inc/parser/xhtml.php