[MonoDevelop] Core / Extras and building

[John Luke]

Hey all,
	I was mucking in the makefiles today to make it easier to run
MonoDevelop with mono -debug (and have it work) and I noticed something.
We have a rather curious Core/Extras split.

Here are my thoughts of what should be moved to Extras:
- language bindings for external languages (Java and Nemerle probably)
- things that are not stable enough to be in Core (we'll make an
exception for the debugger)
- anything with odd dependencies

I actually think MonoDeveloperExtensions can probably move from Extras
to Core.

Last I don't think Extras should be included in the normal auto* build,
as it makes distcheck harder, etc. They should either each have their
own build methods, or one top-level auto setup for Extras.