added file based grammar for D

Now [D](http://dlang.org/) scripts can be executed.

I tested it only on single file programs and it works well. I couldn't get the selection based one to work because of some issues with command line arguments and escaping characters (rdmd is different from other runtime environments in this) but hey, that's something for people that want to try D.

On OSX, just install `dmd` from `homebrew` and it works. Should work on any system with `dmd` installed though (`rdmd` is always included)
This line should be `* D <sup>[*](#asterisk)</sup>`. :wink: