Add some graph query functions
Optimize updates to an edge's label
Use lodash
Initial implementation for copy
Change representation of edges to simplify code
Exploring different internal representations

This approach yields a significant (100x) speedup for setDeleteEdges at
1K nodes, 200K edges, without a significant impact on any other measured
function.
Add outEdges query
Some benchmark refactoring and more benchmark tests
Additional benchmarks
Use 'dot' reporter for mocha
Yet more benchmarks
New implementation optimized with a bias towards reads
Speedup to edges query
~1000x speedup to sources and sinks

We cache sources and sinks at some cost to memory and to the following
mutative functions: copy, delete, setEdge, deleteEdge.
Replace merge with assign for neighbors

Merge tries to recursively merge objects which has some overhead versus
assign.
Optimize edge based queries with aggressive caching