Find/Implement client-side SMT with parameterized tree height

[karlfloersch]

We will need a local SMT which will allow us to implement the state transition & state update logic locally & for tests. Georgios pointed me in the direction of some here:

https://github.com/loomnetwork/plasma-cash/blob/master/server/contracts/Core/SparseMerkleTree.sol
https://github.com/loomnetwork/plasma-cash/blob/master/server/test/SparseMerkleTree.js
https://github.com/loomnetwork/loom-js/blob/d3a74f221ae9f1cbe1ead050d61803854ae418f1/src/plasma-cash/sparse-merkle-tree.ts
https://github.com/loomnetwork/mamamerkle/blob/master/sparse_merkle_tree.go

[Jinglan]

karl got beat by willdabeast