Prior to this commit, the MerkleStore panicked under certain bounds. It
will prevent such panics by using checked operations.
ilog2, for instance, will panic when the operand is zero. However, there
is a documentation rule enforcing the merkle tree to be size at least 2.
If this rule is checked, then the panic is impossible.
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
Bobbin Threadbare
Victor Lopez
Al-Kindi-0