Abstract class for map interaction handlers
https://leafletjs.com/reference.html#handler
Called when the handler is enabled, should add event hooks.
Called when the handler is disabled, should remove the event hooks added previously.
Adds a constructor hook to the class.
Disables the handler
Enables the handler
Returns true if the handler is enabled
true
Includes a mixin into the current class.
Merges options into the defaults of the class.