PEP-484: Support all python type hints

[oxisto]

We should support all the possibilities to annotate types in python.

Example for a type comment (This is parsed as an Assign with type_comment:

a = 42 # type int

Example for a type annotation on variable (this is parsed as an AnnAssign with annotation:

a: int = 42

Example for type annotation on function (this is parsed as returns on the FunctionDef as well as annotation on the arg):

def bar(x: int) -> int: ...

Tasks

Beta Give feedback

1. Python type_comments #1649
   python +1
2. Support stub files from PEP-484 (.pyi) #1640
   python +1
3. Support type annotation on AnnAssign #1656
   python +1
4. Support type annotation on Functiondef and arg