SVGHMI: Alarm test not using Button widget anymore, too many problems. Use Input widget instead to increment value on each click and execute python code on change.

SVGHMI: little fix in HMI:Button

SVGHMI: JsonTable now use intermediate variables again to address JSON data without duplicating code or referencing. Using intermediate variables also alows to check for availability of data and stop evaluating early if data is missing. Finally added complete roundtrip example to illustrate use of JSonTable to display "alarms" collected in python from changes on PLC boolean variables.

SVGHMI: removed debug code forgotten here and there.