Reviving BulletD -- again

[BLM768]

After re-analyzing the magnitude of the project in light of the 
rather lukewarm response I've gotten so far, I think that I may 
indeed have to move to a wrapper system. I'm currently weighing 
my options:

extern(C++) interfaces: From what I understand, these are not 
well-supported outside of DMD, so I think that's out.

A C layer: This seems like the most practical option. I'm 
thinking about using pragma(msg) to generate C code directly from 
the D sources and just redirect the output into C source files. 
Hacky, but probably not too difficult to implement.

Using some sort of magic to directly work with the C++ mangling 
and ABI: Probably the most difficult option, but it would be kind 
of nifty and would get rid of the overhead of a C layer. Probably 
not worth the effort right now, especially considering that it 
would be heavily compiler-specific.