Range.setUpperBound and Range.setLowerBound now check for valid bounds

Added some temporary fields to HierarchicalSplit.Node for debugging

Working on fixing HierarchicalSplit bugs

Added Node.toString method

Parser now initializes Integer RandomSpec range as
[a,b] instead of [a,b)

IMap temporarily exposes getNodesByLevel

Commented bug-print in WorldTree.pickValue

Temporarily made Map.getNodesByLevel public