Added buffer activity to channel list

...a/de/kuschku/quasseldroid_ng/ui/chat/BufferListAdapter.kt

...schku/quasseldroid_ng/ui/chat/BufferViewConfigFragment.kt

app/src/main/res/layout/widget_buffer.xml

app/src/main/res/layout/widget_network.xml

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

...n/java/de/kuschku/libquassel/quassel/syncables/Network.kt

lib/src/main/java/de/kuschku/libquassel/util/Flag.kt