Tests: Fix missing <br/> in generated html report.

Tests: add HTML report generation and a workaround to bad exception handling in sikuli.

In case of exception in python code, and since a thread is running
to observe stdout, sikuli was never terminated after an exception.
Unfortunately sys.exepthook doesn't work in that version of jython/sikuli.
Test are now written inside functions witch are passed to run_test to deal
with exception.

Tests: refactored sikuli based test

IDE: Postpone execution of keyboard shortcut commands when given while previous command is still being executed, to prevent CTR/builder jamming.

IDE: in case of unhandled exception, write bug report to given log file, so that test report can have it.

Merged default's changes in wxPython4 branch

Tests: fix project edit test sikuli IDE test.

Background click based on bitmap matching doesn't work.
Grid dots are not good match candidates.
Rendering probably affected by virtual display's bpp or rasterizer approximations.

runtime, retain: remove forgotten debug code.

Runtime: removing dead code

IDE: removed one (last ?) wx.NewId() that was called on each opening of project tree popup menu

Tests: Re-introduced pytest based tests. Fixed them a bit, commented-out otherwise. Application tests only runs with logging test, and PLCOpenEditor tests seem broken.

Tests: Enhance robustness of stdout driven waiting state in Sikuli based tests.

Some tests were randomly passing, because from time to time waiting for idle was skiped. It was combination of multiple problems :
- buffering on stdout (now use readline + flush for each write to log)
- it is sometime required to wait for activity before waiting for timeout added "WaitForChangeAndIdle" to "stdoutIdleObserver"

Tests: add an IDE test that relies on image matching.

Tests: re-introduce xvfb+x11vnc target in Makefile : xvfb_sikuli