fix commit "lazy initialization of highlight pens and brushes
for DebugVariableViewer" (5562f34f)

clean build example project after running test

fix problem if DataTypeEditor was imported before localization is
loaded

That doesn't affect systems with english locales.

add shell script to run all python tests and automatically handle Xvfb

add PLCOpenEditor tests

run application tests in full screen mode

clean sys.argv, because if test is running from pytest
sys.argv contains string "pytest --timeout 0 ./tests/tools"
Beremiz application parses it and throws exception.

rework Beremiz application "testCheckProject" test to allow easier reuse later