gforth->forth, add colorforth for review

[ng0]

The following 2 patches move gforth.scm to forth.scm as originally intended and 
previously discussed here, and they also add colorforth.
However for the lack of native 32bit or the author providing bad instructions 
(https://github.com/narke/colorForth) I need someone who either tells me this 
is bad, don't add it or who can actually run it..
I'm waiting for a PSU for my old i686 board.
Qemu as build by guix on x86_64 GuixSD when run with "qemu-system-i386 -boot a 
-fda cf2012.img" says
a long version of "nope!" and refuses to fully start this. I'm no expert in 
qemu yet..

[PATCH 1/2] gnu: Rename gforth module to forth.
[PATCH 2/2] gnu: Add colorforth.