Collect all properties introduced and redefined in self

Property definitions

nitc :: model_collect $ MClass :: collect_local_mproperties
	# Collect all properties introduced and redefined in `self`
	fun collect_local_mproperties(filter: nullable ModelFilter): Set[MProperty] do
		var set = new HashSet[MProperty]
		set.add_all collect_intro_mproperties(filter)
		set.add_all collect_redef_mproperties(filter)
		return set
	end
src/model/model_collect.nit:754,2--760,4