4.0.6 - In which many things get better

• Seeds are (again) consistent per-seed. Sorry for the inconvenience.
• Seed randomizing should now work as expected -- only if you leave the seed blank, or if your previous seed was randomized will your next seed be randomized.
• More aggressively blocked re-randomization
• A bunch of work on panel extraction and import, but nothing visible yet
• Symmetry panels should always have an invisible background
• A lot of project cleanup
• Tests!