Implement jellies fixed to black blocks
Fix(?) solved
Solve level 11 \!
Add level 19
Solve level 19
Add test for level 15: this level should be solved (in a very long time)
Re-solve quick levels
Add some tests for emerging jellies
Read and show emerging jellies
Adapt 'solved' to emerging jellies
Read/show all emerging jellies
Implement emerging in stabilize
Solve level 21!
Solve levels 22 and 23
Don't emerge when no room over
Add level 24 (not yet solved)
Improve trace
Solve level 25
Acknowledge that level 26 can't be solved right now
Add level 27 (not yet solved)