Fleetwood66

Released to pick up new xdis version which has fixes to read bytestings better on 3.x

• Handle 3.7+ "else" branch removal adAs seen in _cmp() of python3.8/distutils/version.py with optimization -O2
• 3.6+ "with" and "with .. as" grammar improvements
• ast-check for "for" loop was missing some grammar rules