issue #2789: Adds Map, Dictionary perf test, not yet finished.
Removes unused cast in CCTMXTiledMap.cpp.
issue #2789: Improves performance for Map<K,V>::keys.
issue #2789: Adds performance test for Map<K, V> and Dictionary.
Merge pull request #5127 from dumganhar/iss2789-perf-container

issue #2789: Adds performance test for Map<K, V> and Dictionary.