Collect all classes introduced and refined in self

Property definitions

nitc :: model_collect $ MModule :: collect_local_mclasses
	# Collect all classes introduced and refined in `self`
	fun collect_local_mclasses(filter: nullable ModelFilter): Set[MClass] do
		var res = new HashSet[MClass]
		res.add_all collect_intro_mclasses(filter)
		res.add_all collect_redef_mclasses(filter)
		return res
	end
src/model/model_collect.nit:566,2--572,4