AntonioGonzalez' changes to fix #49
Added map btw Cluster and Marker to DefaultClusterRenderer

This is to make the getMarker method for Cluster<T> faster than
iterating over all the markers in the mMarkerToCluster cache.

Added code to update the mClusterToMarker map each time a marker is
added or removed from the mMarkerToCluster map.

Fixed up some whitespace (to use spaces vs tabs).
Fix issue #60
Fixes Bounds.contains() for issue #71
Update play-services version
Release 0.3.1
Prepare for 0.4 development
Merge pull request #76 from raymondlam/master

Fixes Bounds.contains() for issue #71
Merge pull request #67 from jakeonrails/master

Finish pull request for issue #50 (mapping markers to clusters, cluster items, and vice-versa)
Make methods to get ClusterItem and Markers public

As discussed here https://github.com/googlemaps/android-maps-utils/pull/67
Merge pull request #95 from lukesleeman/patch-1

Make methods to get ClusterItem and Markers public