QtPy is a compatibility layer which allows to use the code written for
PyQt5 with any python Qt binding: PyQt4, PyQt5, pyside or pyside2.

Main differences in PyQt5:

  - all widget classes are now in QtWidgets package, not QtGui;
  - QString obsoleted by unicode (sip API 2);
  - changed the way of signals connection.

Closes: Bitmessage#1191

customwidgets in ui-files and QtGui.QPen instantiation

  - added Qt API string into support request
  - finished flake8 formatting

(for simple encoding like for extended)

(closes Bitmessage#897, closes Bitmessage#1418)

resolved pylint redefined-variable-type warnings,
marked autogenerated modules for skipping by pylint and flake8

on tabs "Send", "Blacklist" and "Network Status":
in qt5 it's probably true by default.

…nts()