Move message processors into their own package
Update ktor

Fix regression with capability negotiation

This allows more options to be added nicely in the future,
and hides the implementation details from library users.

Only annotate internal methods, suppress the messages otherwise,
so users of the library don't have to deal with warnings

Closes #2

Closes #7

To preserve the order of lines we offer them into a channel
without suspending. If we launch a new coroutine there's no
guarantee they'll execute in order, even if the method they
call is fair.

Expose status (connecting, negotiating, ready)
Fire ServerReady and ServerConnected events