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