Sapphire 14 24 ss 1013 deep freeze and deep merge

@tony-spataro-rs added HashTools.deep_freeze! and .deep_merge
the latter differs from deep_merge! because it clones before merging

At this point, understanding #clone and #dup better now, I would agree. We have these public methods already defined, though, so I am only adding remarks to clarify the behavior. deep_clone2 is really a deep dup, yes.