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.