CMake with D support early snapshot

[Trent Forkert]

FWIW, I just pushed my implementation of cmDependsD[1], and found 
dmd-style deps much nicer to work with. I used the >=2.064 
ability to do

     dmd -c -o- -deps foo.d

since that also contains file imports, which are technically 
dependencies. I missed when/if this was discussed on the list, 
but it seems that form of dependency output at least is intended 
to stay, even if it forces us to drop support for older compiler 
versions.

  - Trent

[1]https://github.com/trentforkert/cmake/commit/bbaa6b1f82d6c55154a95d1995007e408c31103e