Encapsulate fields in main class; see #762 #655 #604

src/main/java/fr/xephi/authme/process/register/AsyncRegister.java

@@ -137,7 +137,7 @@ public class AsyncRegister implements AsynchronousProcess {
         }
         database.updateEmail(auth);
         database.updateSession(auth);
-        plugin.mail.main(auth, password);
+        plugin.getMail().main(auth, password);
         syncProcessManager.processSyncEmailRegister(player);
     }