Now that notify-sharp has a 3.0 release that depends on GTK 3, we can
require the proper pkg-config module.
Remove notify-sharp.m4 file, and the useless call to the macro that was
defined in it.
Also remove some unneeded variables in build.environment.mk.
Improve the GitSharp autotools stuff and move it to its own file,
included in the top-level Makefile.
A system-installed nant is now required to build GitSharp, instead of
using the in-tree copy.
All the files we really need to build GitSharp are now included in the
tarball, including the binary deps. I see weeping packagers...
But "make distcheck" doesn't work, mostly because GitSharp insists on
writing to the source dir during compilation. As distcheck builds with a
read-only source tree, this fails horribly.
Pass the proper configure options to SmartIrc4net for bundling.
The SmartIrc4net assembly is now copied into bin/ during compilation,
and installed into the same folder as the other assemblies.
