Prevent a divide-by-zero bug in SHAPE_ARC::ConvertToPolyline.
When the radius is zero, just use the initial angle (it makes
no different anyway, the result is the centre point, which is
the start point.
(cherry picked from commit e312e2b286)
Add unit test of SHAPE_ARC::ConvertToPolyline.
This function has a bug when the arc is of zero radius. This
test shows the bug, but does not fix it yet.
(cherry picked from commit ce84c19a38)
Test a few "centre-point-angle" cases and add some
generic geom code for testing vectors and boxes are within
tolerance (since rounding often creeps in).
Much of the arc-checking code will be useful to other
construction methods (e.g. point-point-point).
There are expected failures for the bbox code when
the arc passes though, but does not end on, a quadrant point
(0, 90, 180, 270). This is due to a defective
implementation of SHAPE_ARC::BBox() that does not take
into account the quadrant points. This will be fixed
as a follow-up.
John Beard