Allow Exceptions to be passed to thread waiting for solutions.
Rethrow exceptions that are placed in queue.
Merge pull request #37 from TeamAmalgam/no-hang

Allow exceptions to propogate from solver thread to main thread.
Merge branch 'master' into amalgam-solution-deduplicator

Conflicts:
	src/kodkod/multiobjective/algorithms/MultiObjectiveAlgorithm.java