plugins: fixes, more work on dynamic querying of plugin hierarchy
plugins: fixes, more work on dynamic querying of plugin hierarchy

shrtcww/pymel,AtonLerin/pymel,david-lassonde-adsk/pymel,leonsooi/pymel,shrtcww/pymel,AtonLerin/pymel,assumptionsoup/pymel,juggernate/pymel,david-lassonde-adsk/pymel,assumptionsoup/pymel,juggernate/pymel,leonsooi/pymel