Implement optional renumbering of node ids as sequentially increasing indices.
Move node renumber classes to util, change internal / external node id variable names, other small fixes.
Add RenumberedGraph example which reads a generated graph into memory both with & without renumbering.
Update RenumberedGraph example to use cleaner approximate byte size of generated graph.
Fix comment typo in unrenumbered graph reading.
Update RenumberedGraph to use existing random graph generation logic. Smaller changes to approx graph size calculation and GraphWriter.
Change RenumberedGraph to not purposely run OOM, but instead compare representation costs of unrenumbered and renumbered graphs.
Fix DirectedGraph approxRepresentationCost to be more realistic in terms of byte cost.
Rename internal variables of SequentialNodeRenumberer to better match new nomenclature.
Update SequentialNodeRenumberer to maintain parallel externalToInternal, and internalToExternal maps to ensure consistency.
Refactor identity NodeRenumberer functionality into NodeRenumberer companion object.
Cleanup old references to IdentityNodeRenumberer.
In RenumberedGraph, Remove commented old code and update docs.
Remove unneeded imports from RenumberedGraph
Code cleanups and add WriteRandomGraph example.
Reorder imports to be in lexicographic order.
Merge pull request #41 from dfuhry/NodeRenumbering

Implement optional renumbering of node ids as sequentially increasing indices. Useful when original nodes do not have ids in increasing order and low space utilization is important.