Added parser tests for ellipsis
Added parsing of ellipsis keyword
Fixed parsing of ....__class__
Added ellipsis type and Ellipsis object to 3.2 stubs
Added type checking of ellipsis
Simplified lexing of ellipsis
Added comment to `ellipsis` class in builtins that it does not really belong there.
Fix typo in comment
Refactor base class representation to be Node

This is needed for namedtuple in base class list.

Still not working!
Fix type checking
Fix semantic analysis
Fix semantic analysis of namedtuple in base class list
Fix source pretty printing of class defs
Add NamedTuple test case
Add NamedTuple test case
Refactor named tuple test cases
Fix type checking with named tuple as base class
Add test case
Add test case for Tuple[...] as base class
Update test cases