adding scatter_inspector_overlay to api.py
adding scatter_inspector_overlay to api.py

burnpanck/chaco,tommy-u/chaco,ContinuumIO/chaco,tommy-u/chaco,ContinuumIO/chaco,burnpanck/chaco,ContinuumIO/chaco,burnpanck/chaco,ContinuumIO/chaco,tommy-u/chaco