twdispatcher does not kill child processes when stopped/restarted

[pads]

When stopping/resarting twdispatcher, the script kills the parent but not the child processes. They are left orphaned and have to be killed off manually.

[cdent]

We may be able to kill -- -$THE_PID

note the leading minus on the pid

(however such things are not working well for @FND in a similar situation)

[FND]

FWIW, my workaround is this: https://github.com/FND/tiddlywebplugins.bfw/blob/013904d92a731a52ecfa8a3ee461dbad934055af/Makefile#L10-11

I suspect the -- -$pid thing might be a BSDism.