Problem::check() more exhaustive

this function is not checking if stateblocks are not nullptr. Independently of verbose_level value, all the state blocks should be checked to be valid.

Also, it would be nice if the problem is not consistent, raising a message explaining the reason apart from updating the variable is_consistent.

And finally, instead of iterating over getStateBlockVec(), iterate over getStateBlockMap() and then the key (string) of each state block can be printed as well.