Refactor Graph class -> GraphSketchDriver + CCSketchAlg

[etwest]

This pull request refactors the key classes of this repository with the goal of increasing the flexibility of our code. We want to allow the possibly for writing code for other sketching algorithms on top of this repository. Specifically, we disentangled the setup for reading and processing graph streams from the code for running the connected components sketch algorithm. We also got rid of the Supernode class and refactored the sketch class to be more usable.

Also some other small stuff, see below.

• Config for driver and cc algorithm seperately
• Extract spanning forest edges option for CCSketchAlg
• Sketch constructor using vector length rather than number of vertices. Add static vec_len_from_verts().
• Graph destructor
• Raw bucket delta update
• Exaustive sample
• Investigate query performance
• More testing
• Rename graph_test.cpp to cc_alg_test.cpp
• See comments below

[DanielDeLayo]

We need to change the sketch interface. Let us input the vector length, instead of the square root of the vector length.

[DanielDeLayo]

The .yml file is much more readable now!

github interface bad