cut build cost in half.

Mimic'd airtightness of standard armor blocks.

Added Half Block and Half Slope Block.
Added <PhysicalMaterial>Rock... Entry to each block So walking on them sounds like walking on rocks :)

Fixed (hopefully) Large Concrete Slab collision.

Deformation Ratio changed from 0 to 0.05
Shifted offset models for large Concrete Slab

uploaded through stable branch.

Bent round block normals to make transitions look smooth.
Added girders back to build requirements.

Removed unused references to build stages in data file.
added 1x3 1x5 3x3 5x5 blocks (tiling issue at certain rotations)

Re-built armor models,new PBR texture, substituted construction models (may keep something similar), added large 1x3, 1x5, 3x3, 5x5 blocks.

Got square plate to show up on blocks