fix #13 and #14
stop following symlinks. fixed some parser bugs.
commenting out msg
one more...
sorry have to reopen #13. something much worse happened after fixing it...
Fix #18. The "with" AST node in Python3 has a different structure. Unified the AST nodes for both Python 2 and 3.
Fixed a "python not found" issue mentioned in #18.
Untangled the logic between Binding and Def.
Fix #21. Forgot to check in Withitem.java :P
fix a stupid mistake
fix offset of Import/ImportFrom
null annotation fix
record super class in ClassType
lots of cleanups for Scope etc
trivial cleanups
add ExtSlice node
remove serialVersionUIDs from AST nodes
simplify over-engineered type printing routines
remove UnknownType. make it a singleton InstanceType.
fix types for constants True, False, None
revert to naive function maps. will generate lots of arrows at the time