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
Made code parsable by mypy
Merge pull request #439 from spkersten/parsecomp

Comparison chaining