If it's a plugin opt, we'll need a callback, so reshuffle logic. Also
add infra to map option name to plugin and option.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Do it slightly intelligently, so if we had set previously using setconfig
we don't keep appending new ones, but replace it in-place.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Currently only implemented for min-capacity-sat.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: JSON-RPC: new command `setconfig` allows a limited number of configuration settings to be changed without restart.
To test, we do min-capacity-sat which is simple. We also update the
listconfigs man page which contained some obsolete information.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>