preliminary work for multiple atomspaces
Minor trite bugfix in error reporting
Add explicit atomspace methods to scheme
Place atomspace into top-level scheme environment

A slight performance slowdown for atom creation,
but adds multi-atomspace flexibility.
Ooops, bugfix to last checkin

Forgot to dereference the variable.
Start work on singleton instance removal.

It has a bad idea, so remove it.
Get rid of the scheme singleton instance.

BTW, the embodiment code that uses scheme seems to be a
massive cut-n-paste job.  It really needs to be completely refactored.
Bug fix the new evaluator code.
Add a new unit test for multi-atom spaces.
Merge pull request #649 from linas/multis

Guile Multi-atomspace work