AHS Extensions -> Coding

1. Just to remember. In my file structure, the planner is separated in three subdirectories.
1. mgp. This one includes the implementation of NAIVE and GREEDY algorithms for the Multi-Goal Planner.
2. shrink. Comprises the implementation of the planner using the shrunken version of the robot. Under development.
3. mpk. This has basically the original MPK implementation, which includes SBL planner. I also added Basic PRM and the AHS implementations. So, under directory prm we have:
   
1. Single Sampler. Corresponds to the Basic PRM.
2. Multi-Goal PRM. Corresponds to Requicha strategy for MG Path planning.
3. AS1: Competing against best fixed weight strategy.
4. AS2: Cost sensitive. U+G+RBB parameterized.
5. AS3: Variable length history.
2. I will work now on the inclusion of visibility-based PRM, so I can run some experiments and make a comparison.