Added parse rule for comparison expressions
Added type checking of comparison expression
Adapted tests for new ComparisonExpr node
Added proper evaluation of resulting type of comparison expressions instead of always returning bool
Fixed DyncheckTransformVisitor for comparison expressions and related bugs.
Removed remaining code associated with OpExpr for 'in' and 'is' operators, which were are handled by ComparisonExpr
Added tests for chain comparison expresions
Removed transform code for comparison expresions
Fix #433. Refactor overloads away in zipfile stubs
Made code parsable by mypy
Replaced overload with Union type in os/path module
Replaced overload with Union types in time module
Merge pull request #442 from spkersten/time434

Replaced overload with Union types in time module
Merge pull request #444 from yczhu/refactor-stub-overloads

Fix #433. Refactor overloads away in zipfile stubs
Replaced bytes/str with AnyStr
Fixed: ConstraintBuilderVisitor created contraint always in SUPERTYPE direction for type vars
Test failure was not reflected in exit status of tests.py

Fixes #454. This should fix travis.sh.
Made local type vars in typing.py stubs private
Renamed all remaining local type vars to start with an underscore
Merge pull request #455 from spkersten/privstub452

Made local type vars in stubs private