Fix bug affecting Azimuthal Equidistant projection -- when the object
was in the center of the field in azimuthal equidistant (for instance,
by doing right click -> Center), the X,Y coordinates would become nan
and the object would not be drawn.

The bug was traced down to an x/sin(x), where the limiting case of x =
0 was not handled, resulting in a 0/0, yielding nan.

BUG