Fixed a few tiny bugs during a routine nullity cleanup

...main/java/de/kuschku/libquassel/client/BufferManager.java

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

...in/java/de/kuschku/libquassel/client/IdentityManager.java

...ain/java/de/kuschku/libquassel/client/NetworkManager.java

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

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

...e/kuschku/libquassel/functions/types/RpcCallFunction.java

.../java/de/kuschku/libquassel/localtypes/BacklogFilter.java

...assel/localtypes/backlogstorage/MemoryBacklogStorage.java

...java/de/kuschku/libquassel/localtypes/buffers/Buffer.java

.../kuschku/libquassel/localtypes/buffers/ChannelBuffer.java

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

...e/kuschku/libquassel/localtypes/buffers/StatusBuffer.java

...libquassel/syncables/types/abstracts/ABacklogManager.java

...hku/libquassel/syncables/types/abstracts/AIrcChannel.java

...uschku/libquassel/syncables/types/abstracts/AIrcUser.java

...uschku/libquassel/syncables/types/abstracts/ANetwork.java

...schku/libquassel/syncables/types/impl/BacklogManager.java

...kuschku/libquassel/syncables/types/impl/BufferSyncer.java

...hku/libquassel/syncables/types/impl/BufferViewConfig.java