Better clause order for SAT solver

[Steffan Sølvsten]

We probably can improve the speed of the SAT Solver examples by sorting the clauses in the following way:

• Break ties on clauses sorted by the same label by the span between its smallest and biggest label. The smallest ones should be done first (similar to the Tic-Tac-Toe example).

• Sort clauses by its first (lowest label) rather than it's last. This may backfire since the lower nodes need to remember more. On the other hand, it may improve the amount of pruning possible - currently, the recursion goes all the way down to a pair of leafs.

[Steffan Sølvsten]

If anything, I'd suggest we completely redo the SAT solver from scratch instead!