Collect all mmethod inehrited,intro and redef

Property definitions

nitc :: mclassdef_collect $ MClassDef :: collect_all_methods
	# Collect all mmethod inehrited,intro and redef
	fun collect_all_methods(mainmodule: MModule, filter: ModelFilter): Set[MMethod] do
		var set = new HashSet[MMethod]
		set.add_all collect_intro_mmethods(filter)
		set.add_all collect_redef_mmethods(filter)
		set.add_all collect_inherited_mmethods(mainmodule, filter)
		return set
	end
src/metrics/mclassdef_collect.nit:123,2--130,4