Push project SchemeInterpreter.

	new file:   buffer.py
	new file:   calc.scm
	new file:   logic.py
	new file:   scheme.py
	new file:   scheme_primitives.py
	new file:   scheme_reader.py
	new file:   scheme_test.py
	new file:   scheme_tokens.py
	new file:   tests.scm
	new file:   tree.scm
	new file:   ucb.py