Simple parametric flat stand/riser

Just a simple way of creating a standing frame for a flat ~thing~ you already have. In my case. I wanted a riser for a sink tool platform whose bamboo platform had tons of ways to get water trapped in it.

#### Features:
* The leg joints/supports can be made square (no support), arched, or chamfered (45° cut).
* There are three different options for support styles (corners only, edges, or edges minus corners(this one is useful for toppers that have rounded corners!) )
* If you don't already have a flat thing to rise, you can optionally generate a topper that's either removable (separate, drop-in) or printed directly into the model.
* You can optionally include a crossbar to further support the topper and/or a corner cross to strengthen the legs.

The example .stl is sized to fit Gridfinity containers and platforms, but does not itself have any Gridfinity-compliant sockets. I might expand on this later.

Since Thingiverse Customizer is somewhat broken, I highly recommend the excellent