SVGHMI: cosmetic fixes + removed dead code

SVGHMI: allow widgets to disable clipping on variables given with min and max. Setting this.clip = false disables clipping.

SVGHMI: allow designating widget's sub-elements as main element child rather than descendant. Names staring with "/" in yslt call to labels() only match direct widget childs.

SVGHMI: add localized Date and Time support to sprintf.js. Use with "%D" or "%2.1D" format style.

Minor changes to README.md

wxPython4 sequels: usual naming problem in grid cell change events, non kw-args to menu.Append and event not being skipped.

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

Fix sequel of wxPython 4 port : double click on tab wasn't maximizing and was showing exception.

Tests: Makefile's PIPESTATUS turned into small letters (wrong vim shortcut ?) leading to always passing tests.

Tests: Various enhancements in Makefile and sikuli common python code.

Tests: Added BEREMIZPYTHONPATH to point to Python interpreter to use for tests.

Documentation/comment fix.

IDE: Fix one more sequel of wxPython4 port : typo in editors/TextViewer.py

Tests: Add a Makefile variable to allow changing standalone headless X server command (Xvfb by default)

Merge default head that was only merged in wxPython4

merged default

Add Docker image definition as reference platform to run IDE tests.

Tests: added tests/Makefile and a first test in tests/ide_tests. Test requires sikuli and Xvfb or Xnest.

IDE: Add -l or --log command line parameter to give a file where all content witten to console window will be appended. File can be /dev/stdout.