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.

Merge default

IDE: follow-up on change in 83ed4ea362db - added workaround when matiec generated files contain unexpected characters.

Runtime : force using monotonic time in Timer (threading). Prevent watchdog to trigger when changing system time.

SVGHMI: remove debug code

SVGHMI: update generated XSLT

SVGHMI: fix again appication of frequency value when given in label. Use it on PushButton instance in svghmi test.

TESTS: moved non-automated tests Beremiz projects stored as directories in /tests to new directory /tests/projects

Create README.md in tests

SVGHMI: update generated xslt, and svghmi test project files

SVGHMI: Add pushbutton widget, that can take reflect short press in variable, but has no garantee on consistency.

SVGHMI: Fixed support for frequency parsing in widget label

Merge

SVGHMI: update generated xslt

SVGHMI test: add special commandline to launch chromium as new intependent window, without GPU acceleration.

SVGHMI: add syntax for widget update frequency in widget label: HMI:WidgetType|freq:arg0:arg1@path

OPC-UA client: "static" class was forgotten for open62541 client structure preventing multiple client.

OPC-UA: cosmetic fix and armless typo

Merged default in wxPython4, include runtimeLists

Merge

SVGHMI: added ListSwitch widget

Merged RuntimeLists branch

Close RuntimeLists branch

Fix bug introduced in previous commit : dual link list wasn't append and remove wasn't implemented correctly. Removed debug code, enhanced variable names and comments.

SVGHMI: optimization of C part : stop traversing the whole HMI tree, use dual linked list for subscriptions and single linked list for changes from HMI. Intermediate commit, still crashing in some cases.

Xenomai runtime: ensure that __DEBUG global variable is set when resuming debug.

SVGHMI: Adapt svghmi.c to changes in UnpackVar

Runtime: Now retain uses a list based on data available in VARIABLES.csv instead of traversing the whole instance tree looking for RETAIN flag.

RUNTIME: Variable forcing now uses limited list and buffer instead of systematical instance tree traversal and in-tree "fvalue" to keep track of forced value for pointed variables (external, located). Pointer swapping is performed when forcing externals and located, with backup being restored when forcing is reset. Retain still uses tree traversal.

RUNTIME: Variable trace now uses limited list and buffer instead of flags in instance tree that was requiring systematical instance tree traversal, and worst size buffer. Forcing and retain still use tree traversal.

SVGHMI: more accurate filtering of elements to unlink or not

OPC-UA client: generated code now take UA_Variants on the stack directly, avoid useless allocation on write, and unalloc implicitely allocated data on read

OPC-UA client: generated code now take UA_Variants on the stack directly, avoid useless allocation on write, and unalloc implicitely allocated data on read

IDE: Tutorial/Example menu was broken : path of project being open was the same for all menu entries.