Basic support for Generators
Currently does not support arguments and only a single generator at a time is allowed

In addition added 'StopIteration' iteration support
Add support for generator arguments
kwargs are unsupported for now
Generators: remove single instance restriction and handle generators inside closures
Merge branch 'master' of https://github.com/dropbox/pyston into generators

Conflicts:
	src/codegen/irgen/irgenerator.cpp
	src/codegen/runtime_hooks.h
Merge branch 'master' of https://github.com/dropbox/pyston into generators

Conflicts:
	src/codegen/runtime_hooks.h
	src/runtime/builtin_modules/builtins.cpp
Slightly change delattr behavior and messages

Not worth producing CPython's error messages exactly: some delattr
messages depend on whether or not the object has a __dict__ allocated
or not.  Just canonicalize those in the tester.
'del name' support

Ended up not being too bad, except for some more fun around classdefs
having different rules, and making sure to generate the correct error
type and messages.
Some basic frozenset support

Just do it by putting a different class object on the same C-level structure.
Not too hard right now to defeat the frozen-ness, please don't try.
Some basic support for the two-arg raise statement
Merge branch 'master' of https://github.com/dropbox/pyston into generators

Conflicts:
	src/codegen/compvars.h
	src/codegen/runtime_hooks.h
	src/runtime/objmodel.h
Generator: implement basic review comments
Generator: fix *args and **kwargs handling
Add issubclass, and fix 0-arg raise statement
Fix bug around instancemethod vref counting
set.__contains__
int methods, and fix a tuple bug
Merge pull request #108 from undingen/generators

Implement Python Generators
Fix crash when passing alot of defaults
Warn more thoroughly about long->int and unicode->str literal conversion
Start adding 'long' support using GMP