Blender Git Loki

Fix T47326: Snap to vertices not working properly in orthogonal view mode.

Same causes as when snapping to faces, so same solution: in case of ortho view,
offset start of ray to be just slightly outside of the target's bbox, to avoid
too much far away start point that generate floating point computation instability
in BVH raycasting.

Note that this lead to some refactoring, to avoid duplicating too much of code.

For now, edge snapping seems to behave OK (uses different logic), so not touched.

Based on patch by Germano Cavalcante (@mano-wii), thanks!