Merge pull request #1615 from millmanorama/subcluster_expansion

...org/sleuthkit/autopsy/timeline/datamodel/EventBundle.java

...rg/sleuthkit/autopsy/timeline/datamodel/EventCluster.java

...org/sleuthkit/autopsy/timeline/datamodel/EventStripe.java

...uthkit/autopsy/timeline/ui/detailview/DetailViewPane.java

...t/autopsy/timeline/ui/detailview/EventBundleNodeBase.java

...hkit/autopsy/timeline/ui/detailview/EventClusterNode.java

...hkit/autopsy/timeline/ui/detailview/EventDetailChart.java

...thkit/autopsy/timeline/ui/detailview/EventStripeNode.java

...timeline/ui/detailview/tree/EventDescriptionTreeItem.java

...utopsy/timeline/ui/detailview/tree/EventTypeTreeItem.java

...euthkit/autopsy/timeline/ui/detailview/tree/NavPanel.java

...hkit/autopsy/timeline/ui/detailview/tree/NavTreeItem.java

...euthkit/autopsy/timeline/ui/detailview/tree/RootItem.java

...t/autopsy/timeline/ui/detailview/tree/TreeComparator.java

...rg/sleuthkit/autopsy/timeline/zooming/DescriptionLoD.java