Binary merkle proofs accepting multiple total values as correct

[rach-id]

Assume you have a merkle tree of 5 leaves. When creating the proof, if you set the number of leaves in [5, 8], the proof going to pass even if {6, 7, 8} are invalid values because with those numbers of leaves, the verifier will behave the same.

Verified with the implementation of tendermint and it also has the same behavior.

Thus, we have thought about this edge case and it doesn't seem to represent any issue. If any arises, we can document them in this issue.

Originally posted by @sweexordious in #253 (comment)