New slotting operation:
- Accepts selection of up to two features.
- Selectable features include: faces, edges, and vertices.
- User may select a single face or edge, or a pair of features.
- The path may be extended at the start and end.
- The path may be reversed.
- The path may be altered to the perpendicular in some cases.
- A unique Slot icon is included.
- Includes simple collision detection with warning message.