Title: Vote to Expell from Federation
Summary: A Federation can expel a realm if enough members vote to do so.
Description: Right now Federated realms can only withdraw individually from a federation. This allows individual realms to ignore whatever terms are set for their Federation and suffer no consequences. In order to retaliate the other realms would have to break from the federation, wait five days for the chance to make peace with each other, spend another two days to get back up to a Federation and then deal with the realm which has been abusing their federation.
Instead there could be a diplomacy option for a Federated realm "Vote to Expel from Federation" this would only be an option for federations of three or more realms. If enough realms vote (it could be either by majority or consensus of the other realms) the offending realm is kicked out of the Federation.
The Federation could default to a given diplomatic stance with the expelled realm. Neutral would be the most practical.
Benefits: Federations have the power to enforce the terms of membership. For example if one of their terms is mutual defense they can expel a realm for refusing to support them in war.
Possible Exploits: a ruler might repeatedly call such a vote despite being rejected by the other realms, resulting in spam. This could be remedied with a limit of how often you can vote. Eventually such an action would frustrate the rest of the Federation most likely resulting in the spamming ruler having his own realm expelled.
