Add ApiGen support

apigen.css was taken from ApiGen's default style.css with 3 changes:
1. All images are inlined as data URIs
2. All styles are restricted to #content
3. The search bar, which doesn't work with Redmine embedded, is hidden
Merge pull request #10 from alexhenrie/master

Add ApiGen support, thanks Alex
Prevent ApiGen content from overflowing the screen

height:100% combined with position:fixed pushes some off the content off
the edge of the window. Also, the splitter doesn't work in Redmine
embedded, so it's better to not display it at all.
Merge pull request #11 from alexhenrie/master

Prevent ApiGen content from overflowing the screen
doxygen.js JavaScript code added
html, js, css inline processing in embedded controller
Fix tab positions for case when no Title present (observend with Doxygen-1.7.3)
All fine except SearchBox
Remove white squre block under SearchBox
SearchBox position
div#MSearchBox .left
margin right for searchbox
div#MSearchBox .left height:21px
Fixed positions for Search Select and Search Results windows
MSearchClose top=0
Allow PDF downloading.
README.md updated
Added support for Valadoc.