Fixed backlog gaps not being removed, added search view

app/build.gradle

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

.../libquassel/localtypes/backlogstorage/BacklogStorage.java

...assel/localtypes/backlogstorage/HybridBacklogStorage.java

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

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

...java/de/kuschku/quasseldroid_ng/ui/chat/MainActivity.java

...quasseldroid_ng/ui/chat/chatview/ChatMessageRenderer.java

...uschku/quasseldroid_ng/ui/chat/fragment/ChatFragment.java

...hku/quasseldroid_ng/ui/chat/util/SlidingPanelHandler.java

...n/java/de/kuschku/quasseldroid_ng/ui/theme/ThemeUtil.java

...ava/de/kuschku/util/irc/format/IrcFormatDeserializer.java

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

app/src/main/res/menu/chat.xml

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