adding docs/* to reference manual

[Havoc Pennington <hp redhat com>]

Hi,

I think a lot of the stuff in docs/* should actually be in the
reference manual so people know it exists and can read it without
getting the GTK source tarball. Propose the following reference
sections for starters:

 - Compiling GTK; covers configure options, etc.
 - GTK on embedded Linux; covers stuff from README.linux-fb, also 
   tips on stripping GTK down to smaller size, etc.
 - GTK on Windows; any details of using it there
 - Debugging; --gtk-debug flags (debugging.txt information)
 - Changes in 1.2, 2.0, replacing the Changes-XX.txt files
 - Memory management (updated refcounting.txt equivalent)
 - Compiling GTK programs (covers pkg-config, debug defines 
   from debugging.txt, etc.)
 - Running GTK apps; command line options parsed by gtk_init()

I'll create the sections for these if we agree it's a good idea, and
move debugging.txt Changes-2.0.txt etc. into them. Probably need Alex
and Tor to do the linux-fb and win32 sections, but I can take care of
setting up the SGML stuff so they just have to type.

These sections would be files similar to
docs/reference/gtk/text_widget.sgml, i.e. not involved in the gtk-doc
templates/scan process at all, just simple documents that should be as
easy to set up as the text files.

Havoc