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.