Robustify pyside

[kristjanvalur]

Runnint the unittests with PySide is sometimes prone to crashing (see #154)
This PR fixes the issues by making lifetime management more robust.

• Timer and signaller objects are parented to the app, for lifetime management.
• QSocketNotifiers are also parented to the app for lifetime management
• QEventLoop.close() is made more robust:
  • The EventPoller is stopped.
  • objects get a .deleteLater() for tidyness in case the __app lives on
  • disconnect() calls are guarded against errors due to different bindings.

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
src/qasync
__init__.py					387, 404
_unix.py					91-106, 123-125, 129-132, 161, 181-182, 186-188, 191-192
_windows.py
tests
test_qeventloop.py					947-956
Project Total

This report was generated by python-coverage-comment-action

[kristjanvalur]

It would appear that the Notifier implementation in _unix.py is not actually used, but I updated it to match the other never the less, in case it ever gets wired in.

[hosaka]

Hi @kristjanvalur, sorry about the delay. I went through your changes. We can probably improve the test coverage, but it's not critical. LGTM.