SVGHMI: DropDown widget now using new class based style

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.

SVGHMI: cosmetic fixes in button widget

SVGHMI: Rewrote button widget.

SVGHMI: update generated XSLT

SVGHMI: stuff test so that it moves all the time, to have better chance to spot memory leaks...

SVGHMI: prevent unwnted context menu and pinch zoom

SVGHMI: more attempts to prevent losing memory in JS closure

SVGHMI: WIP trying to reduce memory usage : use .onclick onstead of SetAttribute, avoid useless closure and object creation when possible, etc.

SVGHMI: update generated xslt file

SVGHMI: use const when applicable

SVGHMI: prevents text and svg elements selection on the whole page when dragging.

SVGHMI: Update default test to check that Input widget is indeed updated when variable changes.

SVGHMI: Fix: on screen keyboard wasn't showing up when editing local variables through Input widget.

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

merge

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

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.

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

Arbitrary variables added to JsonTable subscription are now passed as 'extra' field in json query. As an example added JsonTable filtering in tests/svghmi

SVGHMI: Fix HMI_REAL support, and add a HMI_REAL use case in tests/svghmi.

merge

SVGHMI: JsonTable now outputs "visible" value as well.

SVGHMI: non significant cosmetic changes

- New widget customHtml which allows to insert block of html code
- widget animate transfered to animaterotation
- widget animate, left to be more customizable
- changes to svghmi_v2/svghmi.svg

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

Button fix if no active or inactive state,
Widget animate changed to use anitmateTransform and added option to change rotation
Widget circular slider fixed so it is working on got and reprogramed so it similar to normal slider
Widget slider added support for changing size still need some changes to work properly
Added slider to svghmi test project
Changed svg in svhgmi_v2 project

Merge two different heads