Update docstring
Fix overload resolution
Fix travis.sh to run Python evaluation tests

Ouch, we haven't been running these for a while.
Fix overload resolution bug
Fixes to overload resolution

Still not quite fixed yet.
Fix to overload resolution
Fixes to Python 2 builtins stubs
Fix to Python 2 builtins
Fixes to Python 2 stubs
Fix Python 2 stub of str.__add__

With the latest fixes, we can have a precise signature at last.
Fix type checking overloads with Unions in formals
Another fix to overload resolution
Merge branch 'fix-overload-resolution'