[DNM] - Ports /tg's cable and powernet code to our code base.

Can now cross cables without transferring power between them, and likely also have two 90 degree-cables cross the same turf without connecting.
May also resolve issues with powernets not updating correctly, in particular when placing diagonal cables.

**Remaining issues**
- [ ] Needs to work with breakboxes.
- [ ] APC terminals do not reconnected properly is underlying is cut and replaced.
- [ ] Further in-depth local testing.