[Tilesathome] t at h server doxygen documentation (started)

[spaetz]

I started an effort to get the t at h server code documented in a way that people could actually understand it.
I set up doxygen and got it running quickly. So from now on the t at h server code should always have current documentation.

It is auto-generated every 3h for now on my personal dev space at: http://dev.openstreetmap.org/~spaetz/Doc/html/files.html

Both files and variables can be documented, e.g. http://dev.openstreetmap.org/~spaetz/Doc/html/index_8php.html
as well as functions (I gave NeedRender/index.php a try). Obviously we need to document things before that starts getting a bit more useful.

spaetz