OpenForge Cut-Stone OpenLOCK Half Height Risers

Our OpenForge support of the [OpenLOCK](http://www.thingiverse.com/thing:1833963) is maturing as we add more styles. Here we have all floor tiles in a half height variety. This is great for making higher elevations, or just raised areas like a dias. We have all the square/rectangle varieties here, and in the future, half-height versions of the other morphologies will be added as well.

For instructions on how to get started with OpenForge, we have a set of [tutorials](https://github.com/dev