Added proper backlog filtering, refactored some stuff

app/build.gradle

app/src/main/AndroidManifest.xml

app/src/main/java/de/kuschku/libquassel/Client.java

app/src/main/java/de/kuschku/libquassel/CoreConnection.java

...src/main/java/de/kuschku/libquassel/IProtocolHandler.java

app/src/main/java/de/kuschku/libquassel/ProtocolHandler.java

...va/de/kuschku/libquassel/events/BacklogReceivedEvent.java

.../java/de/kuschku/libquassel/events/GeneralErrorEvent.java

...in/java/de/kuschku/libquassel/events/LagChangedEvent.java

...e/kuschku/libquassel/exceptions/UnknownTypeException.java

...assel/functions/serializers/HeartbeatReplySerializer.java

...libquassel/functions/serializers/HeartbeatSerializer.java

...java/de/kuschku/libquassel/functions/types/Heartbeat.java

...de/kuschku/libquassel/functions/types/HeartbeatReply.java

...rc/main/java/de/kuschku/libquassel/localtypes/Buffer.java

.../java/de/kuschku/libquassel/localtypes/ChannelBuffer.java

...de/kuschku/libquassel/localtypes/NotificationManager.java

...in/java/de/kuschku/libquassel/localtypes/QueryBuffer.java

...n/java/de/kuschku/libquassel/localtypes/StatusBuffer.java

.../libquassel/localtypes/backlogmanagers/BacklogFilter.java