doxyfile and .css changes

updated the doxyfile and .css files
docygen changes

added layout file and edited doxyfile. Tried editing the cmake files to
copy over the doxygen.css and doxygen-layout but couldnt get it to work
updated layout and style

Updated layout and style. Still having issues with the 'closed' and
'open' tags. dynsection.js has to be edited once built and even then the
tables are open by default
doxygen specific changes

Moved doxygen related files to /doc folder. Updated .in and cmake files
accordingly. Tested cmake copying of files
general .css editing

general editing of format from feedback
Added title image

Added an OpenSim logo to the top of the doxygen output
latest .css revisions

patched for IE
code block changes

Improvements to the code block formatting
updated font size

Changed font size for hierarchy page from 14 to 12
updated font, layout and in file

updated to fix some path bugs
fixed images issue and 1 minor bug

made copying the images folder to target a prebuild rather than post.
Updated .in to squash 'teg file (Null)' error. Ran doxygen with no
errors (with latex, dvips and ghostscript installed)
monospace font and line spacing

Adjusted the code block font and updated some of the navigation
linespacing
Merge pull request #183 from opensim-org/jimmydDoxygenExperiment

Doxygen layout and format changes. Moved doxygen related files to opensim/doc