Multiple improvements to UV Cylinder and UV Sphere projection including: * New option "Pinch" or "Fan" to improve unwrap of faces at the poles. * Support for "Polar ZY" option on "View On Equator" and "Align To Object" * Better handling of inputs with round-off error. * Improved handling of faces touching the unit square border. * Improved handling of very wide quads spanning the right hand border. * Improved accuracy near to (0, 0). * Code cleanup and simplification. Differential Revision: https://developer.blender.org/D16869