Multi-Agent A*: 1. Initial naive implementation

[ChrisFugl]

Implement a parallel version as described in page 3 of the paper.

Each agent needs to maintain its own open list, closed list and message queue. The message queue could be implemented by the Java class ConcurrentLinkedDeque.

This implementation should not care about verification of stable properties (that is for step 2 and 3 of the implementation plan). Neither should it care about moving agents in parallel (that is for step 4).