Merkle implementation (#139)

* add: merkle tree implementation

* add: merkleitem

* fix: remove changes

* fix: merkle tree

* update: cargo.toml

* add: vec sort and node impl to merkle ree

* fix: lint errors, remove duplicates from leaves

* fix: merkle tree

* fix: lint errors primitives

* fix: cargo toml conflict

* remove: unused merkle package

* modify: merkle_tree remove vec

* fix: lint error

* fix: remove clones, correct keccak256 hash

Author: samparsky