Change our mypy configuration to disallow untyped defs by default, which ensures *new* files added to the code base are fully typed.
To avoid having to type-annotate everything now, add `# mypy: allow-untyped-defs` to files which are not fully type annotated yet.
As we fully type annotate those modules, we can then just remove that directive from the top.
cx_freeze doesn't seem to be very well supported in Python 3.5.
Using pyinstaller instead and rename environment to "freeze" which
is a more generic term for freezing python code into standalone
executables.
Fix#1769
Bruno Oliveira
Anthony Sottile
Ronny Pfannschmidt
Andras Tim