Added some missing properties to the AbstractEdge.clone() method.
add filter for categories
Optimized the collapseEdges() function and added a unit test for it.
fix alarm list page bug
Merge branch 'space/13.2' of github.com:OpenNMS/opennms into space/13.2
updates on alarm and event list page
add configurable category prefix for CategorySearchProvider
Updated unit tests with more coverage to track down issues in SPC-787.
Optimised collapse functions inside VertexHopGraphProvider so that
collapsing groups no longer causes unnecessary slowdowns.
don't set a default prefix
Update errorhandler to not show stacktrace window
Added source and target labels to AbstractEdge.toString().
Changed search providers to return emptySet() to avoid NPEs when centering
on categories with zero vertices.
Added Criteria varargs to a bunch of getVertex() methods in VertexProvider.
Overrode these functions in VertexHopGraphProvider so that vertices that are
derived from CollapsibleCriteria can be fetched from the methods. Cleaned up
VEProviderGraphContainerTest.
updates on alarm and event list page from OpenNMS branch