Mega commit - discipline fail.

* Cross-assembly dependencies implemented
* Some compile-time validation implemented
* Container.Create rewrites are awesome
* Unused-binding detection implemented

TODO:
* Fix out-of-order validation problems, i.e. if Example happens to be
  validated before LibraryExample, things break.  Can we get build order
  from Fody?  If not, maybe build the dependency graph ourselves :(
* Wire up Fody pipeline, for reals
* Integration tests
* Set bindings, maybe, if anyone asks for them