Some progress today:
* The solver can now remove a piece of dirt to be able to move a rock in some cases.
* It can make some use of trampolines.
* It has a panic mode that tries to fix things when it doesn't know what to do.
Still to do:
* Remove rocks in general, when blocking other stuff.
* Stop stuff from falling and blocking other stuff.
* Handle beards.
* Handle lambda-rocks.
* Deciding in what order to do stuff.