Runtime: Fix bugs in Linux target.

- next occurence absolute time computation failing on 32-bit because of casting
- PLC thread was started before period was set, potentially passing uninitialized timespec to clock_nanosleep()

runtime: Change Linux target to use clock_nanosleep instead of timer (better rt-preempt perf).

Linux runtime: fix thread waiting on wait_RT_to_nRT_signal not being waken-up when delete_RT_to_nRT_signal is invoked.

Tests: docker image needs tesseract4, but opencv lib since sikuli.jar already contains it.

More explicit default value for generic makefile target command. Assume Makfile is located in project_files

IDE: prevent IDE/CLI process surviving to sys.exit() by using deamon threads to monitor external processes output streams.

Tests: allow overriding local host's hostname with BEREIS_LOCAL_HOST env variable.

Tests: IDE: explicitely wait for build success rather than just stdout to become silent.

Tests: Fixed wrong path (relative to $HOME) in CLI tests.

Tests: OPCUA tests can now use OPCUA_DEFAULT_HOST environment variable to force host to something else than "127.0.0.1" or "localhost"

IDE: fix segfault when unselecting network discovery in URI editor

IDE: fix exception when showing project's context menu in case of empty clipboard (wxpython4).

Tests: Fix dockerfile not finding locales.

cosmetic fix

Tests: use expedited termination of IDE with SIGTERM instead of normal close

Work around test not finishing when IDE ask for confirmation on exit when
project is modified.

IDE: When receiving SIGTERM signal, kill runtime befor bailing out without saving.

Purpose is to allow expedited test termination.

Merged default in wxPython4 branch

tests: IDE: own text matching logic for OCR reliability, enhanced ihtml report

SVGHMI: update generated XSLT files

examples: add "csv_read" project to demo CSV access from PLC

py_ext: add CSV file reading POUs in python extension library

SVGHMI: fix input widget sometime messing with font style

Merged default in wxPython4 branch

ST code generator: when including PLCopen TC6 XML libraries (for example py_ext/pous.xml or NativeLib.xml), also includes libraries globals in result

Runtime: add arbitrary file upload to working dir in web interface

SVGHMI: fix double-dispatch happening when using low widget update frequency on variable already being updated with high frequency by other widgets.

Merge

Backed out changeset ddadbdf20e70, no effect on current problem.

GH CI: try reverting to previous version of ubuntu

IDE tests: ensure that file browser idled before entering path in new_project

tests/tools: move comment and remove dead code in Dockerfile

tests: add tesseract training data "tessdata", still trying to enhance OCR reliability in UI tests

tests: attemps to make OCR based hits more stable

Tests: fix path logic in Docker creation script, consequence of previous commit.

Tests: cleanup and tidy docker definitions and scripts

Merged changes from default in wxPython4 branch

SVGHMI: fix XY graph init (consequence of earlier change) + reindent

Earlier change did modify the variables attributes (options) are stored in widget objects. XY graph uses variables' min and max to determine range.

SVGHMI: move declaration of "xmlns" javascript const so that widgets can use it.

This was broken in earlier commit, when changing initial execution order because of implementing websocket reconnect.

SVGHMI: add Page assignment use case in svghmi test project.

Marged default in wxPython4

SVGHMI: update generated xslt

SVGHMI: avoid Widget's member name colision in between enable expressions and assignments.

SVGHMI: Add arbitrary variable assignment when entering Pages

Usage similar to Assign widget.
Required instanciating PageWidgets for each page, so that assigned variables can be subsribed.

SVGHMI: update generated XSLT

SVGHMI: fix periodic reconnect triggering watchdog

IDE: Optimization of modification events processing in text editors.

Too many modifications types where registered, and then too many events were fired.
Also, in case of uninterrupted sequence of events, updates to the model is deferred to the end of that sequence (wx.Callafter).

SVGHMI: cosmetic change

SVGHMI: do not try to reconnect websocket if closed properly by server.