The subscription changes in drum broke existing subscriptions. This
worked alright (though loud) for dojo, but it left chat-cli "frozen"
unless you manually unlinked/relinked. This does that automatically.
It also includes a refactoring of +on-load in drum, to avoid vain
repetition.
At some point this should be more properly styled similar to +by, +in,
and +to, but for now this reduces duplication and makes the ordered map
available to everyone.
Uses Zuse's previously unused +harden helper function to streamline
+task unwrapping in vanes.
(Arguably, in landlocked vanes like Ford, we should crash if we get a
%soft task, since no events should be coming in directly from the
outside.)
This broke when %kick was handled by resubscribing on your own ship
because it processed the %kick before the %leave. For example, `@t`404
at the dojo would put the dojo in an unworkable state.
You want the %leave to be processed first because you can't do a
"resubscribe" in response to that.
