Fix memory leaks on reloads

[MillhioreBT]

Pull Request Prelude

• I have followed [proper The Forgotten Server code styling][code].
• I have read and understood the [contribution guidelines][cont] before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

These changes will cause that when you do /reload the scripts will be cleaned from the reference table, this way there will be no memory leak.

The only case that is not covered is /reload items, for some reason this method produces an increase in memory on each reload: bool Items::loadFromXml()

Issues addressed: Nothing!

[nekiro]

Looks pretty good, I'll check this in-game soon

[NRH-AA]

Finally.