TurboCase 1.8.0

* Support putting all the OpenSCAD metadata inside footprint properties
  so TurboCase can generate cases that include footprints that are not
  from the same version.
* Generate a placeholder case outline when loading a PCB without any
  drawings on the User.6 layer. This is just a rectangle with a bit of
  padding around the bounding box of the PCB.
* Use fuzzy matching for connecting the Edge.Cuts shapes into a board
  outline since KiCad also allows slight gaps due to rounding errors.