Redis [NEW] keyspace notifications should use integers/defines instead of strings for keyspace event types

The problem/use-case that the feature addresses

Currently the keyspace event are sent with a string (ex "loaded" "new" "del" "rename_from" "rename_to"). So the handler that a module writer implements has to do a lot of string compares. This seems ugly for both code aesthetic reasons (can't use a simple switch on type) and perhaps even speed (lots of strcmp).

Description of the feature

types should be replaced with a integer constant/define. For backwards compatibility, can have a new subscribe function and if a user subscribed to the old one, then it's easy for redis to simply fire the event with a simple lookup into a static char* array based on the integer value and issue it with the correct type string.