Slate Building

• Arrow slits have an outside and an inside now, as a castle's do: outside the wall stays flat with the slit alone, inside the opening splays wide so you can aim to the sides. They are placed with the wide side towards you. Slits already built keep their place and their direction and open to the south or the east: to turn one round, break it and place it again from the other side (suggested by Drywall Consumer).
• Swap wheel: new option "Open where it was left" (off by default). The wheel opens on the wheel you used last, the pointer on the shape you picked there: nudge the mouse and let go to pick it again. It is kept over a restart, and the build menu's wheels keep their page too (suggested by Drywall Consumer).
• New shapes on a new wheel page, Fittings: doors, trapdoors, scaffolds and crates, made of any block like every other shape (suggested by Drywall Consumer).
• Doors and trapdoors work as vanilla's do: a click or redstone opens them, villagers open the doors, and they sound like their material (wood like its wood, stone and metal like iron). A door is one item and two blocks; breaking either half drops one door.
• Scaffolds are climbable frames: walk into one from any side, jump to climb, sneak to sink down through it, and stand on its slatted deck from above. They need no support and never fall.
• Crates hold 9 stacks, open under their own name ("Oak Crate"), work with hoppers, comparators and other mods' pipes, and spill what they hold when broken. Building modes treat them as containers.
• A door or trapdoor whose short name is a vanilla one keeps its material's whole name ("Oak Planks Door", next to vanilla's Oak Door).

Slate modules need the Slate Core of their own version: update all of them together.