SVGHMI: Check that explicit relative page jump path is consistant with destination page reference path.

SVGHMI: ForEach Widget now has a better wrap-around when scrolling : hit the boundary systematically before wrapping

SVGHMI: Alow relative relative Jump. (i.e, relative jump from a foreach widget)

SVGHMI: Generalize applying cache to widgets, be it from page or ForEach widgets. Now ForEach widget buttons work as expected.

SVGHMI: Widget ForEach buttons now call corresponding methods.

SVGHMI: ForEach now has working (un)subscribe. Fixed PageSwitch that wasn't behaving when jumping to current page with another path.

SVGHMI: Easier way to match HMI tree elements to paths. ForEach widget now looks for paths and indexes of all items, and enforce path to be consistent with ForEach items sub widgets

SVGHMI: added func:get_hmi_tree_elt to match HMI tree node from path. Continue implementing ForEach widget : force order and completeness of items list. Now also collecting ForEach buttons.

SVGHMI: ForEach knows its own widgets

SVGHMI: add widget_foreach.ysl2

SVGHMI: make root HMI tree node a HMI_NODE, droped HMI_ROOT node type

SVGHMI: reworked widget (un)subscription now a method of widgect object, allowing special subscription methods

SVGHMI: Exclude (again) sub-widgets of forEach widget from page-switch managed widget.

SVGHMI: cosmetic changes

SVGHMI: Simplification and optimization. func:parselabel becomes a template.

All labels are parsed into a global variable containing resulting widget
description as a node-set. func:widget(id) was added for random access to
widget description.

SVGHMI: intermediate untested state. Excluded ForEach widget from pages handled widgets.

SVGHMI: update Makefile to pick all changes to any dependency

SVGHMI: created widget_*.ysl2. Renamed widget_common in widgets_common, so that it doesn't match globing.

SVGHMI: moving comments

SVGHMI: added widget_common.ysl2

SVGHMI: More readable debug output gen code

SVGHMI: Cosmetic changes

SVGHMI: added inline_svg.ysl2

SVGHMI: detachable_elements.ysl2 becomes detachable_pages.ysl2, and includes logic to process pages elements. Other minor code moves.

SVGHMI: moved debug code

SVGHMI: created detachable_elements.ysl2

SVGHMI: more debug code moved to hmi_tree.ysl2

SVGHMI : create hmi_tree.ysl2, rename bbox_intersect.ysl2 into geometry.ysl2 and move more code into. Add per included ysl2 file debug output.

SVGHMI: created bbox_intersect.ysl2

SVGHMI: Re-enable dispatch to arrays of functions in case of multiple suscription per widget. Still unused, but disabled for reasons not any more true.