It would be lovely to have a global, persistable memory available. That is, add an attribute global_data or such to the Dispatcher class, that can be passed to handlers and is integrated in persistence.
This would make it easy to process stuff that can be changed by multiple different chats.

Putting this here, because I don't know when/if I will be able to open a PR. If someone is faster than me, please don't hesitate ;)