Updated gdmd/gdc man pages

[Anders F Björklund]

The manual pages for GDC were from 2004,
so a bit out-of-sync with recent options...
e.g. It was missing D interface files and
Ddoc documentation options, and some others.

I posted two updated man pages at:
http://www.algonet.se/~afb/d/man/

Proof-reading / suggestions appreciated,
so they can go into the GDC distribution.
(generated TEXT/HTML for easy reading...
But normally those wouldn't be included)

--anders