Openforge 1.5x2 base

There are multiple versions of the tiles: one with walls on the edge of the grid and one that sits inside the grid.

Walls on the edge of the grid are usually disconnected from the floor, where as wall inside the grid are printed with with floor.

This is a base for attaching walls inside the grid--disconnected from the floor but still sharing half a grid width.

This is untested as it was requested by someone.