fix tree bug where removes would fail
fix tree bug where removes would fail

the width or height of the rtree rectangle created by extentRectangle
would be negative. These rectangles insert ok, and are found by search,
but they cannot be removed.

issue #1370

edpop/iD,1ec5/iD,energiekollektiv/openmod.sh-id,bagage/iD,1ec5/iD,tbicr/iD,kepta/iD,tbicr/iD,AndreasHae/iD,mapmeld/iD,edpop/iD,ngageoint/hootenanny-ui,AndreasHae/iD,morray/iD,edpop/iD,digidem/iD,openstreetmap/iD,ngageoint/hootenanny-ui,zbycz/iD,bagage/iD,openstreetmap/iD,digidem/iD,openstreetmap/iD,mapmeld/iD,kartta-labs/iD,kartta-labs/iD,zbycz/iD,andreic-telenav/iD,ngageoint/hootenanny-ui,kartta-labs/iD,energiekollektiv/openmod.sh-id,morray/iD,AndreasHae/iD,kepta/iD,mapmeld/iD,andreic-telenav/iD,bagage/iD,1ec5/iD