fixed issue #205. only allow iterables to be dropped on tabular editor
fixed issue #205. only allow iterables to be dropped on tabular editor

NMGRL/pychron,UManPychron/pychron,UManPychron/pychron,NMGRL/pychron,USGSDenverPychron/pychron,NMGRL/pychron,NMGRL/pychron,USGSDenverPychron/pychron,UManPychron/pychron,UManPychron/pychron,USGSDenverPychron/pychron,USGSDenverPychron/pychron