V0.5.0 - Storage fixes

This release includes some minor fixed to the storage package which required some breaking changes.
We are releasing these breaking changes because we reached the conclusion that the current interfaces
are prone to bugs, or inefficient. Unless you are using these specific interfaces, you should be able to upgrade from 0.4 without issues.

Breaking

• Removed the implementations of Clone for storage types which are not useful and may cause data corruption if used incorrectly.
• Changed Keymap::insert to take the item by reference rather than by value. This should reduce the cost of calling that function by avoiding cloning.

Features

• Changed the implementation of the add_prefix methods in the storage package to use length prefixing, which should help avoid namespace collisions.