MarkerLabel isLabel detection, Removal of MarkerParentModel custom handling of a Marker. It is to now use MarkerChildModel which should allow MarkerParentModel to be removed.
rectangle clean/destroy bugs, MarkerParentModel deleting with Marker Api to MarkerChild working
specs fixed issue #681
removal of dead Label/ MarkerLabel code
_.object to zip up IMarker keys for Marker->MarkerChildModel keys
Merge pull request #735 from nmccready/develop

issue 681 MarkerLabel creation and MarkerParentModel is gone