Add timespec() and channel_override logic -- so we can install a time specification with which the channels are driven, but yet allowing a human override (either by RPC or by Button)

src/rpc.c

@@ -118,6 +118,7 @@ static void rpc_channel_set_handler(struct mg_rpc_request_info *ri, void *cb_arg
   } else {
     channel_set(idx, (bool)value);
   }
+  channel_override_set(idx);
   mg_rpc_send_responsef(ri, "{idx: %d, relay_state: %d}", idx, channel_get(idx));
   ri = NULL;