Arch Tiles A2

As requested by JargonJC!

  1. Optimisation update

    B!scuit
    Aligned the tiles to the grid for to work better with larger grid scales
    Retextured for easier artpassing with texture replace
    "Sewers" now have their round bottoms placed below them
    (This is so you can switch between flat and curved floors)

    Now with an example section!
    (Including transitions between sewers and catacombs)