Reserve all built-in names.
Add test case to stop this breaking again.
Fixes #45.
Reserve names used as keyword arguments.
Reserve names found in assignment statements.
Add test cases.
Fixes #43.
Avoid unnecessary enumeration and lookup.
add .gitignore (for python and vim)
preserve top-level names and make usable as module
(#47) Fixed __builtins__.__dict__ erroneous behavior
Merge branch '47-__builtins__-problem'

Conflicts:
	minipy.py
fixed error when handling Assign on preservetoplevel case