Not only we can import modules by full path, but now we can also spawn
threads/coroutines and exchange data in between them with the same
primitives and semantic as in Go.

The bulk of new functionality is copied from here:

	kirr/go123@9e1aa6ab

Original commit description follows:

"""
golang: New _Python_ package to provide Go-like features to Python language
- `go` spawns lightweight thread.
- `chan` and `select` provide channels with Go semantic.
- `method` allows to define methods separate from class.
- `gimport` allows to import python modules by full path in a Go workspace.

The focus of first draft was on usage interface and on correctness, not speed.
In particular select should be fully working.

If there is a chance I will maybe try to followup with gevent-based
implementation in the future.
Hide whitespace changes
"""