Fix autocomplete, add topic editing, fix settings

...main/java/de/kuschku/quasseldroid/ui/chat/ChatActivity.kt

...de/kuschku/quasseldroid/ui/chat/input/ChatlineFragment.kt

...va/de/kuschku/quasseldroid/ui/chat/topic/TopicFragment.kt

app/src/main/res/values-de/strings_preferences.xml

app/src/main/res/values/strings_preferences.xml

app/src/main/res/xml/preferences.xml

...a/de/kuschku/libquassel/quassel/syncables/BufferSyncer.kt