Separate Solid Operations and Solid Tools into different projects

[Eneroth3]

These solid operations were originally created to be used inside of other extensions, not as standalone tools. To make them easier to include in any extensions they could be split off into its own repo, with a clearly documented and tested API. This library could then be used both by Eneroth Solid Tools and any other extension.

[LuluWalls]

Yes, that was taken into account. The new solids.rb file should be a drop in replacement for your original solids.rb file. There are no (intentional) changes to the old interface.

In the new repo you'll find test_models/test_shapes.skp which contains a half dozen shapes that failed to subtract/trim properly with original algorithm.

[Eneroth3]

This is an independently logged issue about the long term plan for Eneroth Solid Tools/Operations. The project has been dormant for a while and I had forgot to document this intention.