added support for areas-of-interest to be respected by triangulations; cleaned up and commented code

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branch : ltl-safety-cosafety
added world, to represent propositional truth assignments

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branch : ltl-safety-cosafety
added automaton, which runs on sequences of worlds

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branch : ltl-safety-cosafety
added propositional decomposition, which supports propositional regions within a decomposition

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branch : ltl-safety-cosafety
added product graph, representing a triplet of decomposition, co-safety automaton, and safety automaton

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branch : ltl-safety-cosafety
added LTL planner

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branch : ltl-safety-cosafety
added convenience class for creating propositional triangulations

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branch : ltl-safety-cosafety
added demo program for LTL planning with triangulations

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branch : ltl-safety-cosafety
added helper method for generating avoidance safety automata

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branch : ltl-safety-cosafety
updated ltl demo to use avoidance safety formula

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branch : ltl-safety-cosafety
merged from default

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branch : ltl-safety-cosafety
Added LTL boilerplate classes to assist users in setting up LTL planning problems. Just hand a robot's SpaceInformation and ProductGraph to LTLSpaceInformation, and all is taken care of under-the-hood. Updated demo to demonstrate usage.

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branch : ltl-safety-cosafety
merged

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branch : ltl-safety-cosafety
made LTLPlanner issue a warning when given more than one start state. Removed support for replanning from a specified ProductGraph state.

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branch : ltl-safety-cosafety
cleaned up LTLSpaceInformation formatting

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branch : ltl-safety-cosafety
addressed TODOs within LTLSpaceInformation

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branch : ltl-safety-cosafety
cleaned up LTLProblemDefinition formatting

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branch : ltl-safety-cosafety
removed feature for partially satisfying co-safety formulas

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branch : ltl-safety-cosafety
changed demo to no longer print triangulation

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branch : ltl-safety-cosafety
changed getNumRegions to be pure-virtual in Decomposition

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branch : ltl-safety-cosafety