NONE: Hardened BF-directed hypergraph element binding; HGL module benchmarks

[SpectraL519]

• Refactored the hypergraph implementation to throw when trying to bind a vertex to a head/tail set of a BF-directed hyperedge when the vertex is already bound to the other set of that hyperedge
• Introduced HGL module benchmarks:
  • hg-bfs: Comparsion of traversal performance using the native undirected hypergraph representation and an equivalent traversal on a corresponding incidence graph
  • hg-b-bfs: Comparsion of traversal performance using the native BF-directed hypergraph representation and an equivalent traversal on a corresponding incidence graph

[SpectraL519]

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