Extreme negative flow at end of vase mode gcode processed with -z

[malventano]

A simple cylinder vase mode gcode, when processed with ArcWelder and -z (--allow-3d-arcs), ends with an extremely high negative extruder flow value. So high that it throws the flow scale when previewing the processed gcode.

Result with Arc Welder:

Result without Arc Welder (circled code that appears to have been incorrectly converted to an arc):

Before/after gcode attached:
arc welder extreme negative e.zip

May be related to #90

[malventano]

Attempting to ping @FormerLurker as it seems he has been inactive for some time.

[malventano]

Additional info:
Looks like this happens any time there is a wipe, which contains a few (smaller) negative extrusions, which Arc Welder is fitting into a very large one. A simple fix would be an option to abort arcs which contain negative extrusions. -v won't catch these so is not suitable as a workaround.