Changes Underground Belt and normal Transport Belt to be able to replace one another. Underground Belt can be placed directly on top of normal belts for much faster BUS alterations.

BONUS: For 0.15 includes updated code for Thadorus' Quick UG Belt mod (all credit goes to him for creation and following description). When placing an underground belt over an existing line of regular transport belts, automatically removes the unconnected regular belt in between the endpoints of the underground belt.

Instant belt removal has two modes, normal and safe. Safe will only remove belts if all belts between endpoints are facing the same direction as the underground belt. Normal will always remove belts that face the same direction as the underground belt. You can cycle through the two modes and disabled using a keybind (default ctrl-U).

Changelog: 1.5.3 -- Fix neighbors nil crash introduced with Factorio 0.15.13