Added a add alias command

The command will create a `define-alias` for the current symbol if required (i.e. there is not already a `define-alias` for the same type)

The command will also change the current symbol to the alias value. So, the command can be used to convert fully-qualified class name to an existing alias.

The types `Object` and `String` never trigger a define-alias addition and the fully qualified name for those types are converted to their simple class name (running the command on symbol `<java.lang.String>` will result in `<String>` and no `define-alias`).