fixed bar coloring doesn't match legend coloring
worked around metric toggling bug - last visible entry can't be disabled
Merge branch 'master' of github.com:wikimedia/limn into develop
metricRef -> metricDef (oops) and properly serializes metricRefs in ColumnDef
Fixes serialization of DashboardTab
GraphNode and GraphNodeData now support invoke() and pluck() down the tree.
Cleanup.
Fixes zooming.