Emacs & D wiki update

[Bill Baxter]

I updated the info on emacs at Wiki4d, for any y'all using emacs for 
your D coding.

In particular I spent way too much time today figuring out how to get 
M-x compile to actually take to to the source given DMD compiler error 
messages.

Note to Walter:  *all* error messages should be prefixed with "Error" 
"Warning" or "Remark" if you want emacs to grok them out of the box. 
Currently it's hit-or-miss.  Some of them are, some of them aren't.

--bb