Splits ModuleRegistry#auto_add_ports()
Splits ModuleRegistry#auto_add_ports()

This takes the decoding logic, decode_input_port() and
decode_output_port(), out of auto_add_ports().

hjanime/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,minesense/VisTrails,hjanime/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,minesense/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,minesense/VisTrails,Nikea/VisTrails,hjanime/VisTrails,Nikea/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,minesense/VisTrails,hjanime/VisTrails,minesense/VisTrails