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.

SVGHMI: relative pages and page jumps

SVGHMI: take care of path given in HMI:Page and HMI:Jump, but do not apply subscription offset for now. Intermediate commit in a "working" state.

SVGHMI: significant whitespace changes

SVGHMI: unsignificant changes or changes in generated code

SVGHMI: Stop ignoring HMI_NODE in HMI tree, and count it as a BOOL. Soon we use those nodes as reference for relative page jump, and as an "enable" bit for features associated to an HMI tree fragment.

SVGHMI: cosmetic code moving

SVGHMI: split page switch into switching subscription and switching elements in the DOM, to ensure that subscriptions have been send before changing DOM, and avoid some flicker.

SVGHMI: fix wrong updates of HMI variables on each change, especially when not subscribed.

SVGHMI: whitespaces

SVGHMI: fixed repeated error when Input widget is missing 'value' element

SVGHMI: more decoupling in between UI related and the rest of JS code, still in the aim of enhancing robustness under heavy load.

SVGHMI: use requestAnimationFrame to delegate rendering of updates from network. Should help prevent browser collapse leading to watchdog in case of overload.

SVGHMI: Fix disapearing elements in case of nested detachable elements.

SVGHMI: Meter widget accepts 2 arguments : min and max, taken in account when min or max text element is missing

SVGHMI: More precise error message on missing HMI path. Meter widget now defaults 0-100 range when min and max elements arent's present, without error.

SVGHMI: more whitespace fixes

SVGHMI: unlink clones (i.e. deep copy elements refered by svg:use) inside widget.

Designer can use Inkscape clones to duplicate similar assets accross widget. Those clones are unliked so that elements can be independently transformed by individual widgets.

SVGHMI: whitespaces and comments

SVGHMI: completely fixed indentation of generated widget description. Lets try to keep it as-is until we can use yslt indentation.

SVGHMI: re-indent generated JS

SVGHMI: detach/re-attach elements required by pages on page switch

This is meant to optimize performances with large drawings leading to long restyle or reflow.

SVGHMI: re-indenting

SVGHMI: declares pages detachable requirements as an object, to find more efficiently common requirements

SVGHMI: fix some JS + add generation of detachable elements, to be continued