added dontRecomposite
SuspendEvents also suspends recompositing on CompositeDynamicObjectCollection
Issue: https://github.com/AnalyticalGraphicsInc/cesium/issues/1452
make `shouldRecomposite` 'private' as `_shouldRecomposite`
performance fixes
Iterate over _collections vs _collectionsCopy
Merge branch 'composite-performance-fix'
Merge remote-tracking branch 'origin/master'