The Welcome class prints a message if the server recommends a CLI version
that's newer than what the client is currently using, but only if the client
is running a "release" version, not a "local" development one. "local"
versions have a "+" in them (at least when Versioneer creates it), but
Welcome was looking for "-" as an indicator. So it was printing the warning
when it shouldn't be.
re-enable the test, and add an extra one
The comments in cmd_send/cmd_receive now enumerate the four cases where we
might notice that things are taking too long, the three cases where we say
something about it, and the two cases where it might be appropriate to give
up automatically (although we don't do that anywhere yet).
