modbus plugin: add/fix comments

merge

Modbus plugin: fix bug - map BOOL flag onto C u8 (was incorrectly mapped onto u16)

Modbus plugin: map status of MB transaction onto 2 located BYTE vars (instead of a singlw WORD var).

Modbus plugin: provide user programs feedback on current connection status mapped onto a WORD located variable

Removed harmful assert in ProcessLogger.

ProcessLogger was having an assert in constructor when missing logger, leading to systematic exception when testing options accepted by compiler. This exception was silenced in ProjectController, and then MatIEC was always called without options.

Fix missing import, consequence of bad resolution of conflicting hg graft of f0a822ef9fa0 into d15a997859b1

plc_debug.c/var_acces.c : whitespace cleanup and other cosmetic changes

Prevent global python_poll blocks to be created when accidentally adding content to C-File OnChange column.

DEBUG: (IDE side) fixed wrong implementation of anti-rapid-fire leading to systematic delay in subscribing

XSLTransform.py: added get_error_log()

Attempt to workaround problem reported about empty plc.xml after unrelated crash. Now, if etree model is corrupted in a way tostring() would generate an empty string, exception prevents saving.

docsvg.py : Better error message when inkscape is not installed.

Fix unmatched "Courier" font for monospace fonts on latest ubuntu 20.04. Selected "FreeMono" instead, present since at least 18.04

Python Runtime: order of execution of extension's init() and cleanup() now reflects order of appearance of extensions in configuration tree.

Runtime: change PLCObject 'BlobAsFile' method to allow customization by overriding

WebInterface: better wording for wiping PLC content: "Repair"

runtime: added restart/reset button in web settings. Accidentaly fixed web settings logging feature.

Add a little test to see OnChange's .count .first .last in action

Fixed "Onchange" object added in previous commit

Python Safe Globals now have more reliable triggering of OnChange call. Added "Onchange" object to accessible runtime variables that let user python code see count of changes and first and last values.

Project tree: avoid flickering and glitches in notebook when selecting some still not opened ConfigTreeNode

Project tree: Clicking on ConfigTreeNode should have same behaviour as for POUS and other IEC types : simple click to select and double click to open.

py_ext: better handling of coma separated OnChange attribute for python safe global variables.

Allow customization of generated py_ext OnChange calls, by adding a static method to PythonFileCTNMixin that can the be later hot patched.

PY_EXT: OnChange is now a coma separated list of callables. Updated tests/python accordingly.

Modbus: fixed typo in ctype typing.

MODBUS: Fix saving of websettings.