drawEllipse function bug

[maxwelllc]

In all instances of the drawEllipse functions in bresenham.c that I used while testing in Picross, there were floating dots that seemed to correspond to the midpoint of the horizontal lines of the bounding box. I didn't look too far into it, so I don't know what the root cause is.

[AEFeinstein]

Can be addressed post-magfest