Adds comments

src/main/java/ch/hepia/Main.java

src/main/java/ch/hepia/events/ChatMessage.java

src/main/java/ch/hepia/events/Event.java

src/main/java/ch/hepia/events/Meeting.java

src/main/java/ch/hepia/models/User.java

src/main/java/ch/hepia/mq/Message.java

src/main/java/ch/hepia/mq/MessageManager.java

src/main/java/ch/hepia/mq/MessageQueue.java

src/main/java/ch/hepia/ui/ConnectionController.java

src/main/java/ch/hepia/ui/MainWindowController.java