[PATCH] mscoree: Implement ICorRuntimeHost::CreateDomain{, Ex}(). (try 2)

[Vincent Povirk]

It might be possible to invoke AppDomain.Id on the new (proxy) object,
use mono_domain_get_by_id to get the MonoDomain*, then invoke
AppDomain.CurrentDomain to get the real AppDomain object in that
domain.

BTW, I think I made a mistake when I added the domains list. We should
probably just rely on Mono to keep track of domains (other than the
default domain), so we can be aware of domains created by calling
AppDomain methods directly.