Merge pull request #2124 from bfroehle/use_alias_magic Add an API for registering magic aliases. Add a method `register_alias` to `MagicsManager` which can be used to register new magic aliases. Each magic alias is an instance of `MagicAlias`, a helper class whose `__call__` looks up the target of the alias (at call time) and dispatches the magic call. As a future benefit, this could be easily extended to allow for new aliases which contain some flags to pass to the function. For example, it would be easy to change the behavior to allow the creation of an `%ex` alias for `%edit -x`.