Implement semantic analysis of Undefined(type)
Add test cases for Undefined(type)
Add test case
Update docstring
Add missing type annotations
Add basic support for new type application syntax
Analyze type applications with multiple types
Add type application test cases
Code layout fix
Update docstring
Add basic semantic analysis of type aliases
Add type alias test case
Support qualified type aliases
Add type application test cases
Translate some checker test cases to new syntax
Disable most checker test cases for now

Will enable more cases when the current ones pass.
Remove unneeded empty line from test case
Do not type check 'typing'

This module is special and cannot be type checked.