Merge changes from default into svghmi branch

SVGHMI: More build time optimization : def_by_label now takes far less time.

SVGHMI: Optimize sumarized_elements xslt function, taking most of SVGHMI build time.

Merge

SVGHMI: Add icons

SVGHMI: Fixed/extended error message when failing to launch POEdit.

SVGHMI: Fix launch of POEdit on widows. Parsing oommand in registry based on heuristic was bad, now using regex should be safer. TODO : replicate for Inkscape launch.

SVGHMI: display progress in IDE console while building

SVGHMI: finally found why HMI:Input wasnt't initializing properly: vsprintf takes a list. Also, removed intermediate variable last_val, since edit_value() works on strings anyhow, and in case of formated floats, it is better to workl on already formated value.

SVGHMI: update generated XSLT

Allow printf-like formating in HMI:Input, usefull for example when dealing with floating point numbers.

SVGHMI: Switch from {object} to Map for "updates" global, for performance but also preventing wierd behaviour when iterating

SVGHMI: Fixed HMI:ScrollBar to exclude cursor size from accessible range ( position is now 0->range-size instead of 0->range ). Fixed and extended tests/svghmi to have working ScrollBar on two alarm pages. Includes generated XSLT update.

SVGHMI: JsonTable removed useless promise since fetch() already does one. Updated generated XSLT.

SVGHMI: Optimization for JsonTable : reload JSON only when necessary, and avoid concurrent http requests.

merge

SVGHMI: update generated XSLT

SVGHMI: little fix ihn i18n example.

SVGHMI: Fixed sending HMI_REAL to PLC. Added a svghmi_real test that illustrates using printf style formating in HMI:Display to control precision of Float number display.

SVGHMI: i18n: ensure langs always appea in same order, and add two variables that are updated automatically when selecting a new language : lang_name and lang_code. Also fixed i18n startup, prevent wrong lang numer to crash loading.

SVGHMI: more straightforward implementation of dragging position computation in Scrollbar + some little fix about boundaries.

SVGHMI: allow i18n of formated strings of HMI:Messages. This was by construction impossible since formating was given as an argument. Now added optional "format" labelled element in HMI:Display, so that it can be translated, when labelled "_format".

SVGHMI: update generated XSLT

SVGHMI: i18n: prevent creating messages.pot if no translation

SVGHMI: Add inhibition to widget's apply_hmi_value() so that it does not change variable more frquently than given widget's frequency. This prevents flooding network with many update if browser is producing events at high rate, as for exemple when dragging ScrollBar's cursor.

SVGHMI: fix scrollbar not behaving when rotated.

SVGHMI: remove forgotten debug code

SVGHMI: Add a robust ScrollBar widget. HMI:ScrollBar@positionrange@size

SVGHMI: propagate default local variables (HMI_LOCAL, PAGE_LOCAL) to widgets at startup

SVGHMI: Update generated XSLT

SVGHMI: HMI:DropDown:#langs@lang now automatically shows human readable list of languages. tests/svghmi_i18n updated accordingly.

SVGHMI: Add a simple i18n test

SVGHMI: Prevent Dropdown widget to mak exception whe value out of range

SVGHMI: removed dead code

SVGHMI: Add "lang" permament persistent HMI_LOCAL variable to reflect selected language, apply stored language choice at startup and make it always subscribed to a pseudo widget (as for hearbeat) that apply language choice when it changes.

SVGHMI: Added HMI:VarInitPersistent to initialize persistent HMI_LOCAL and PAGE_LOCAL variables, stored as cookies in browser.

SVGHMI: Enforce formating HMI_LOCAL and PAGE_LOCAL variables until the end of variable name

SVGHMI: generate JS translation literals so that it is possible to also translate uses of texts, and added JS code that apply translations to tspans

SVGHMI: widget activable elements : moved code to wher it belongs, rewrote cleaner

SVGHMI: update generated XSLT

Merged

SVGHMI: make a copy of tests/svghmi as test/svghmi_widget because too crowded since having pages for widget documentation. Strip those pages from tests/svghmi, so that it
is more light for regular testing.

SVGHMI: Prevent excluded widget to appear in generated pages' widget list.

SVGHMI: Remove recursive walk in parsed widget to find unique type and use xsl:key instead.

SVGHMI: Fix browser side exception when some widget are not used, and are then discarded and not present in final SVG. In that case JS code was still making reference to discarded widget elements and was raising exception at init.

SVGHMI : removed support for changing keyboard position and showing at user defined location. Feature was problematic in many respect.

SVGHMI: Make an error when pages are nested

SVGHMI: i18n: finished passing back translated messaged to xslt proc, finished template to generate corresponding javascript literals.