Save the proxy password so you don't have to reenter it after restart

src/models/network.js

@@ -538,6 +538,7 @@ Network.prototype.export = function () {
 		"proxyPort",
 		"proxyUsername",
 		"proxyEnabled",
+		"proxyPassword",
 	]);
 
 	network.channels = this.channels

test/models/network.js

@@ -49,6 +49,7 @@ describe("Network", function () {
 				proxyEnabled: false,
 				proxyHost: "",
 				proxyPort: 1080,
+				proxyPassword: "",
 				proxyUsername: "",
 				channels: [
 					{name: "#thelounge", key: ""},