Order dependent handlers.

[pharaun]

We want to have threading and concurrency in the ircbot to handle slow-handlers and so forth, however the primary issue would then be handlers that depends on a particular order of irc messages to work properly.

Should implement:

1. some sort of pre-filter that slaps on something like an auto-inc integer to track "total ordering"
2. have a pre-handler or option for ensuring that an handler can only ingest messages in a specific order
3. The main gotcha is how to expose this feature and how to make sure that the handlers can all be multi-threaded yet only process messages in a specific order for specific ones (can probably just block those order-dependent ones and make sure they process it one by one)