rewrite confirm of signs when requiring planes, now we do not need any explicit input of signs;
fix the error when using even resolution as bg mesh resolution;
add simple primitive cone and box
Note: Cylinder's side surface defines its AABB, and z-axis scaling does not affect its radius.
Degeneracy checks only consider x/y directions (first two rows of the transform matrix), since z scaling does not change the essential geometry.
TODO: Consider redefining cylinder so the identity transform is always the first subface.
Zhicheng Wang
mckay