More comments, more readable code
Less copying and cleaner code
Ooops, bug, forgot to type 'return'.
Giant bug: tertiary clauses were not handled in blocked clauses
Print number of solutions found until now
Nicer printing of multi-solving
Adding more comments to solution extender
More assert() in SolutionExtender
Much cleaner and more commented SolutionExtender
Move forward&backward flips to separate functions
Don't pick replaced variables during solution extension