Automatically dispose the ViewportSizeMonitor
Dispose the tiles removed from the cache
Fix WKT writers output type
Merge pull request #2423 from fredj/dispose

Dispose the tiles removed from the cache
Merge pull request #2448 from gingerik/wkt-docs

Fix WKT writers output type.
Add ol.ClusterFeature.
Correct ol externs definitions.
Add ol.source.Cluster.
Add tests for ol.source.Cluster.
Add example for clustering.
Listen to goog.events.EventType.CHANGE instead of 'change'
Add missing olx.source.ClusterOptions#extent property
Add missing olx.source.ClusterOptions#smallestCluster property
Add missing olx.source.ClusterOptions#distance property
Remove ol.source.Cluster#getResolution function
Remove ol.source.Cluster#setResolution function
Remove unnecessary quotes
Remove property privacy in ol.source.Cluster
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