using util event system

pom.xml

src/main/java/info/kwarc/sally4/client/EventBusContext.java

src/main/java/info/kwarc/sally4/client/EventHandler.java

src/main/java/info/kwarc/sally4/client/EventListener.java

...n/java/info/kwarc/sally4/client/EventListenerFactory.java

...main/java/info/kwarc/sally4/client/EventListenerList.java

src/main/java/info/kwarc/sally4/client/IActionAcceptor.java

src/main/java/info/kwarc/sally4/client/SallyClient.java

src/main/java/info/kwarc/sally4/client/SallyDoc.java

src/main/java/info/kwarc/sally4/client/Subscribe.java

src/main/java/info/kwarc/sally4/client/TestSallyClient.java

...ain/java/info/kwarc/sally4/client/impl/MessageParser.java

...n/java/info/kwarc/sally4/client/impl/SallyClientImpl.java

...main/java/info/kwarc/sally4/client/impl/SallyDocImpl.java