Implemented theme serialization to a file

src/main/java/envoy/client/ui/ChatWindow.java

@@ -81,6 +81,7 @@ public class ChatWindow extends JFrame {
 			public void windowClosing(WindowEvent e) {
 				try {
 					localDB.saveToLocalDB();
+					Settings.getInstance().save();
 				} catch (IOException e1) {
 					e1.printStackTrace();
 					System.err.println("Could not save localDB");