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.