Avoid `Clone` in `FenwickTree`

[TonalidadeHidrica]

Current implementation of FenwickTree clones the values to be added, but in principle, these operations can be done by just passing reference. I changed the trait bound so that it now requires reference values can be added, and removed the Clone bound.

This PR depends on #102 (this dependency is not actually necessary, but when it comes to combining these two, it will require a certain amount of rollbacks, so I created a new branch from that branch.)