Merged default in wxPython4 branch

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.