Create: Pit & Gantry

Added

• Unbreaking on drill heads. Every drill head can now be enchanted with Unbreaking I to III (anvil and enchanting table). It works as on a vanilla tool: a mined block costs no durability with chance level / (level + 1). The new server config value unbreakingEffect (0.0 to 1.0, default 1.0 = vanilla, 0.0 = no effect) weakens it. Efficiency and Mending are still not accepted.

Fixed

• The drill head no longer teleports over air. Where there is nothing to mine (air, skipped blocks, drained fluids), the head now travels to the next block at a steady speed, and that block is only mined once the head is there. Moving on to the neighbouring block never waits, so normal mining is as fast as before. The travel speed is the new server config value headTravelSpeed (blocks per tick, default 0.5). The head position is saved and synced, so it does not jump on a reload or when a player joins.
• Gantry rig: the bridge is now gripped on both ends, and the far leg runs on a rail. A gantry carriage directly under each end of the bridge holds its rod (it used to hover half a block above the supports). The far leg's wheel now rides on a drawn gantry rail along the far rim, which lies on the ground of each column and steps with the terrain. The rim is read at most once a second instead of every frame.