Renaming of functions with better understanding of reconnects. Under
the original logic, reconnecting blithely created a new session if
the original no longer existed. Now it will alert the user when this
happens.
Also hopefully fixes#381 as there was a bug of missing argument not
being caught by lisp's undisciplined typing.
Upon disconnection, the jupyter server apparently returns the same kernel for a given
notebook path input. So reconnect is a thing, and restart is very
distinct from that.
Fixes#377
Coursera appears to kill websockets every minute or so, and I'm
observing firsthand the buggy behaviors described in #356. This PR
cleans up the websocket code and kernel restart logic. Removed
backwards compatibility for the v2 messaging api
as keeping it in the presence of the refactoring would make it more
broken that it already was.
