Multiple bugfixes for align and distribute on circle.
- don't crash when dealing with empty objects, closes #5926 (closed)
- don't crash/produce broken transformation when applying to single object, closes #1095 (closed)
- always pick correct side of arc, closes #5919 (closed)
- fix full circle sometimes getting treated as 0deg arc, closes #2690 (closed) , closes inbox#12603 (closed)
For the last two issues code now uses existing SPGenericEllipse method to determine if ellipse is whole and thus 360°. Previously it just always read start/end angles and made assumptions based on those, which could lead to inconsistent interpretation of what the shape of ellipse/arc is. Couldn't quite reproduce the buggy case on my system. @Moini could you test if this MR fixes inbox#12603 (closed) for you.
Also removed some unnecessary y axis up/down usage from the manual coordinate branch. Either both of the angles should use them or none. Previously setting angle from 45 to 90 depending on yaxis direction resulted in 45° or 135° arc which is definitely wrong.