Added initial D language support.

Added initial [D language](http://dlang.org/) support.

This is based on quite an old patch that's been floating around for a while. Even though it is old and could be improved, it does indeed work.

This is a recent discussion on the D newsgroup regarding ctags support:
http://forum.dlang.org/thread/klcykihcmttwqqupzgpg@forum.dlang.org if this pull request is accepted i'll direct them here instead of maintaining yet another repo.