[patch] some geometry fixes

[Tom Tromey]

>>>>> "graydon" == graydon hoare <graydon@redhat.com> writes:

graydon> these two patches fix some problems in geometry: AffineTransform was
graydon> mis-transforming points in some cases, and Arc2D wasn't returning a
graydon> path iterator which approximated an arc segment very well. 
graydon> ok to commit?

Yes, thanks.
One little note...

graydon> +      else if (e <= 90 * (Math.PI / 180))

I think it would be a bit cleaner to just write `e <= Math.PI / 2',
i.e., reduce the fractions.

Tom