Add handling for text spam

[spark-c]

It would be nice if the bot were able to keep track of how many/how frequently a user is sending messages in a channel, and time them out / delete their messages as appropriate if they are sending too many messages in a short period of time.

Ideally the parameters of "too many" and "too frequently" would be configurable by at least guild, and even better if it were configurable by role as well.