v0.2.1 - The only good bug is a dead bug

Would you like to know more?

This releases fixes a good dozen bugs, including ones that prevented new projects from being created ☹️. The performance of project builds has been improved, and this release fixes some bizarre bugs that would happen if the scene editor was open when the project was rebuilt. Finally, some features like "New Game" and "Undo" were added to the Solitaire example game.

With this, I'm ready to start the next feature phase of development, which will involve scene transitions (pre-loaders) and tile maps (to create a Sokuban-type game).