[v3] initial Doxygen doc-generation support added

[Benjamin Kosnik]

> Anyone?  Anyone?  What do y'all think of just listing public members for
> J. Random User?  Maybe we can use this as a starting point for discussion.

how about public member functions and all (public/private/protected) member 
data? That would be pretty useful.

I guess I'm a bit confused about the maintainer/user separation too. I 
think we might want to just start with a universal config, and then 
if/when maintainer-specific data becomes useful, we can split it off. 

-benjamin