Implement the freenode.net/identify-msg vendor cap

[edk0]

There's no prior art, so we can change the capability name to something charybdis-y if you have a domain and you want to.

m_identified gets to be a core module because we need to maintain identified status at all times—there's no way to recover it after module downtime. I suspect m_services should get the same treatment, but that'll be another PR, if so.

[kaniini]

if they are authed to an account, that should be sufficient. what is this identified thing about?

DALnet-style NICK ownership has never been a design concept in charybdis, why should we make it one now?

[kaniini]

If we were to implement a DALnet-style nick ownership mode, it should be implemented with a user-mode, not this module approach. That allows it to be an extension, which is basically the only thing that is tolerable.

[kaniini]

Here's how we are going to actually do this.

We are going to add a usermode +r, which can only be set or cleared by services. On nick change, the usermode will automatically clear. This will NOT be a required module to run charybdis, it will be an extension. Freenode will simply enable the extension.

Instead of adding yet another ENCAP, we're going to add ENCAP MODE to allow services to set this user mode. Other ENCAPs should also be replaced by ENCAP MODE.

[kaniini]

Closing in favor of #357 which is a design that is acceptable to us.