Add execution tests for default arguments and if none expressions
Allow variables to change type
Add TODO to README.rst
Remove completed TODO items
Narrow types in if-else bodies if condition checks for type
Check all passed types when looking for common super type
Use types.union when finding common super type of unrelated types
Add missing module
Perform type narrowing when condition is "is not None"
Support type narrowing when if condition contains isinstance check
Add types for dict methods
Bind class name before type-checking class
Add parsing for type statements in isolation
Add parsing of type definitions
Fix type definition parsing
Parse type name as reference node
Revert "Parse type name as reference node"

This reverts commit 7c491acec7ad77252128b4fdad23b7e3918b0389.
Add type definitions to visitor
Add name declaration for type definitions
Add type inference for type definitions