Example formatted MerkleTree:

```
880abe452320966617646e7740b014954300f19a28780a0889d62ff33f4b0534
  1ade1369091efa31201e9b60c9c28874d0ddce5362b335135a6bb4c917285983
  3e60a9c843b4bb19f7a0572102e6507195f5240767a396335fd21981b048b807
    0100000000000000000000000000000000000000000000000000000000000000
    0200000000000000000000000000000000000000000000000000000000000000
    0300000000000000000000000000000000000000000000000000000000000000
    0400000000000000000000000000000000000000000000000000000000000000
```

Example formatted MerklePath:

```
[0400000000000000000000000000000000000000000000000000000000000000, 1ade1369091efa31201e9b60c9c28874d0ddce5362b335135a6bb4c917285983]
```

This commit introduces a wrapper structure to encapsulate the merkle
tree traversal.

related issue: #36

A Merkle path is a vector of nodes, regardless of the Merkle tree
implementation.

This commit introduces an encapsulation for such vector, also to provide
functionality that is common between different algorithms such as
opening verification.

related issue: #36

This commit moves the previous implementation of `SparseMerkleTree` from
miden-core to this crate.

It also include a couple of new tests, a bench suite, and a couple of
minor fixes. The original API was preserved to maintain compatibility
with `AdviceTape`.

closes #21

closes #5