SVGHMI: Fix multiple variable support in widget

SVGHMI: Add TODOs in Button widgets.

SVGHMI: Alarm test not using Button widget anymore, too many problems. Use Input widget instead to increment value on each click and execute python code on change.

SVGHMI: little fix in HMI:Button

SVGHMI: JsonTable now use intermediate variables again to address JSON data without duplicating code or referencing. Using intermediate variables also alows to check for availability of data and stop evaluating early if data is missing. Finally added complete roundtrip example to illustrate use of JSonTable to display "alarms" collected in python from changes on PLC boolean variables.

SVGHMI: removed debug code forgotten here and there.

SVGHMI: JsonTable now makes meaningfull JSON request : all arguments and variables are passed in.

SVGHMI: Keypad is now keeping Javascript type constency. In other words, if a number was given as initial value, input value will have to convert to number in order to be valid. In case invalid value is entered, initial value is restored.

SVGHMI: Behave when project path include spaces, and make more understandable error in case of problem extracting geometry with inkscape.

SVGHMI: Refactor the way JsonTable generate javascript code to access json data. Now support multiple assignments, used in the case of text to change both content and style on the same element.

SVGHMI: Fix again clone unlinking, and this time add an "original" attribute to track the id of the original object before unlinking.

SVGHMI: Fix svg test file while testing latest JsonTableChanges

SVGHMI: HMI:JsonTable also recognize TextStyleList, but parsing of textContent is still not implemented and style is still not updated.

SVGHMI: Deeper clone unlinking. Was actually not recursive, and clones in clones where not unlinked. Stack successive ids to avoid collisions.

SVGHMI: factorize dispatch calling logic.

SVGHMI: HMI:VarInit:"a string"@a_value : empty widget (i.e. empty svg:group) that initialize content of local variables to value given as first argument.

Merge

SVGHMI: Add more local HMI variable tests in tests/svghmi.

SVGHMI: finished initial implementation of PAGE_LOCAL and HMI_LOCAL variables.

SVGHMI: add a SetPoint to Slider Widget, visible only when operating the slider.

SVGHMI: Update Slider widget so that it doesn't display future value but actual value only.

SVGHMI: provide request_animate() to Widget authors so that they can register redraw code when events lead to redraw. Widget member animate() is called when it is time to update DOM.

Merge

SVGHMI: Intermediate state while implementing local HMI variables. Now write to cache only (no send), still need to implement dispatch on change.

Beremiz test project with newly created widgets.

Rebuilded gen_index_html.xslt after all new widgets were commited

Create new multistate widget which extand class widget

Create new CircularSlider widget which extand class widget

Create new slider widget which extand class widget

Reworked togglebutton widget to extand class widget

Changed keyboard to show on defined position.

* svghmi.js
added size paramter to edit_value
changed show_modal function to offset keyboard if paramter passed

*widget_input.ysl2
in on_edit_click:
function get position if key_pos element is defined in input widget

*widget_keypad.ysl2
Reworked keypad widget to extand class widget,
added support for changing keyboard position to user defined location

Reworked button widget so it uses classes.

SVGHMI: allow multiple variables and formatting in Display widget. Formatting is printf style and given as first argument. If no formating is given as widget argument, space separated.

SVGHMI : have to move some JS declarations from "preamble" to "declarations" and others from "declarations" to "definitions" section to make room for JS libraries that would be used by widget classes.

SVGHMI: JS refactoring continued : "dispatch_value_to_widget" becomes widget class member "new_hmi_value" (was also broken by previous relativeness commit)

SVGHMI: widgets are not anymore binary relative or absolute, but have a "relativeness".

Because of allowing multiple variables per widget, we must distinguish if individual variables is relative to page, not the whole widget.

SVGHMI: More JS code refactoring : change_hmi_value and apply_hmi_value now methods of widget class.

SVGHMI: Better JS code semantic in ForEach widget class. Update lagging generated xslt.

SVGHMI: Add ForEach Widget is svghmi test

SVGHMI: add get_idx(index) to widget objects to factorize a bit code repeated accross widgets. To be continued.

SVGHMI: prefer apply_hmi_value() to change_hmi_value() when possible

SVGHMI: Add RelativePages to tests

SVGHMI: Update Widget Display templates to generate Class based declaration.

SVGHMI: JsonTable now picks items from HMI:List, and update texts, all according to Json data. Still miss scrolling.

SVGHMI: JsonTable now generate working data access code for data/* elements.

SVGHMI: Minimal support for HMI:List : clones pointing to elements of any HMI:List are never unlinked, widgets using HMI:List will rely on this.

SVGHMI: minimal JSON Table Widget communication infra + corresponding python code as py_ext code in svghmi test. To be continued.

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