Fix doubleclick on line to create a point (closes #4691)
Fix doubleclick on line to create a point
(closes #4691)

kartta-labs/iD,kartta-labs/iD,bagage/iD,bagage/iD,ngageoint/hootenanny-ui,kartta-labs/iD,mapmeld/iD,mapmeld/iD,ngageoint/hootenanny-ui,AndreasHae/iD,bagage/iD,AndreasHae/iD,morray/iD,morray/iD,openstreetmap/iD,ngageoint/hootenanny-ui,openstreetmap/iD,digidem/iD,openstreetmap/iD,AndreasHae/iD,mapmeld/iD,digidem/iD