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.