Implement Global Type checking

[hasii2011]

Use mypy to do static checking; this is even more than PyCharm checks

[hasii2011]

These modules require more elaborate fixes (I put # type: ignore)

• ErrorManager
• PyutPythonVisitor
• DebugErrorViews

For the following see: realpython. (# type: ignore # override)

• PreferencesCommon (handle *args or **kwds)
• DebugPreferences
• BackgroundPreferences
• MainPreferences

[hasii2011]

Not going to do this. I don't like Mypy's strictness and how hard it is to exclude stuff; I like the incremental approach I can take with PyCharm