Setpoint handler and writing to points

The SetPointHandler sets incoming setpoint values to control writable control points.

ID.

This is an example of setpoint handler JSON:

 {
   "%idKey%" : "x",
   "%valueKey%" : y,
   ("%slotNameKey%" : "slotName")
 }

The Control Points are located by handle ord in the form: "%idKey%" : "323e" or "%idKey%" : "h:323e".

These properties configure setpoint handlers:

idKey is a top-level key in the JSON payload. It represents the point ID.
valueKey is a top-level key in the JSON payload. It represents the value to set.
slotNameKey is an optional top-level key in the JSON payload. It represents the slot name to write to.
defaultWriteSlot defines which slot to write to by default if the payload does not specify a slot.
runAsUser is a mandatory property for the setpoint handler to use.

The nested keys, override/duration and status are not currently supported.