Rename Slave to Host

The role of a slave as a host for Factorio servers is not well reflected
in its name and has caused confusion among users.  Rename slave to host
to better reflect its role as a host of Factorio servers.

plugins/global_chat/instance.js

@@ -45,7 +45,7 @@ class InstancePlugin extends libPlugin.BaseInstancePlugin {
 
 	async onOutput(output) {
 		if (output.type === "action" && output.action === "CHAT") {
-			if (this.slave.connector.connected) {
+			if (this.host.connector.connected) {
 				this.sendChat(output.message);
 			} else {
 				this.messageQueue.push(output.message);