SVGHMI: Fix bug in keypad leading to error messages in browser console when keypas has no Shift or CapsLock keys

SVGHMI: cosmetic changes

SVGHMI: Input widget overrides undershot() and overshot() methods to display "min: xxx" or "max: xxx" when user input goes out of given range.

SVGHMI: Added clipping to min and max value for all widget using @path,min,max syntax. Added overshot() and undershot() methods to widget base class, called when value is limited to max or min respectively.

SVGHMI: decoupled operation string evaluation from HMI variable uptdate in change_hmi_variable(), paving the way for min/max boundaries enforcement

SVGHMI: Added parsing of min and max value that can be given as @path,min,max in widget description

Merged default in svghmi branch

WebInterface: better wording for wiping PLC content: "Repair"

SVGHMI: almost rewrote Input widget to make it new class based style.

runtime: added restart/reset button in web settings. Accidentaly fixed web settings logging feature.

SVGHMI: added dropdown selection highlighting and fixed scrolling so that it doesn't miss any entry while jumping from one page to the other.

SVGHMI: change scroll buttons into single unicode triangle and center them. Use highlight rectangle duplicated and hidden to catch selection clicks so that the whole row is clickable.

SVGHMI: DropDown widget now using new class based style

Add a little test to see OnChange's .count .first .last in action

Fixed "Onchange" object added in previous commit

Python Safe Globals now have more reliable triggering of OnChange call. Added "Onchange" object to accessible runtime variables that let user python code see count of changes and first and last values.