Loop videos

See merge request !599

(cherry picked from commit 9fbcaff5)

(cherry picked from commit 228883a7caf1ef2b61cb84b22eaee08e790371c0)

"Add fast scroll for images"

See merge request !597

Feature Request  force english language

Closes #280

See merge request !595

- moved the logic that change the locale in `BaseActivity`
- every activity extends `BaseActivity`

- Changed "launchMode" of PlayerActivity from 'singleInstance' to 'singleTask'
  to allow more than one activity to participate in LeafPic's Task Stack.

Added Timeline Action Menu, refactoring

See merge request !592

- fix view holder icon

- Added interfaces to BaseMediaGridFragment for Context
  Menu and getters for updating the Toolbar.
- Added kotlin-android-extensions for Synthetic
- Added icons for Share, Delete, Select All
- Added hack to unreference fragments in MainActivity.
- Added MediaUtils to hold common code for Media Items.
- Converted TimelineFragment to Kotlin :)

UI changes:
- Timeline now has Share, Delete, Select All functionality.

Added Kotlin support, MultiDex, refactoring.

See merge request !591

- Added Kotlin support to the app. Welcome, Kotlin! :)
- Added MultiDex support. We finally hit 64K methods!
- Refactored BaseFragment. Moved EditModeListener and
  related interfaces to BaseMediaGridFragment for easier
  extension of Media Grid fragments.
- Removed unnecessary listener setters from MainActivity,
  we can use onAttach for these.
- Fixes crash and behavior #590

- added security check on delete media
- removed deprecated stuff

- added disposeLater in SingleMediaActivity

- created ErrorCause
- Created ProgressException

- Added Filter (Images / Videos / Gifs / All) to
  Timeline Fragment's menu.
- Updated albumsMode implementation in MainActivity
  to fragmentMode to clearly handle different modes.
- We now have the Timeline header text dependent on
  device theme.
- Minor fixes.

* Added Timeline Support via Experimental setting

- Moved MediaListener to a separate interface.
- Added Timeline default grid sizes: Portrait - 4, Landscape - 5
- Added DeviceUtils utility class for getting Android device data.
- Added menu_timeline.xml to inflate the ActionBar menu.
- Added support to refresh items when Grouping Mode is changed.
- Added support to store the header text in TimelineHeaderModel.
- Added GroupingMode enum to sort the Timeline items.
- Added TimelineItem interface to specify that a given header / media
  is capable of being a Timeline item.
- Added Timeline ViewHolder class to store the TimelineHeaderViewHolder
  and TimelineMediaViewHolder classes and binding logic.
- Updated TimelineAdapter to use List of TimelineItems and
  recycle the types. Removed MediaAdapters.
- Updated TimelineHeaderModel to use Calendar instead of Date.
- Added TimelineItem, optimised RecyclerView implementations
- Added support to show Timeline in Navigation Drawer
- Added TimelineFragment to show the timeline.
- Added TimelineAdapter to show the Timeline contents.
- Minor refactoring at various places.

TODO
- Clean up implementation
- Add media selection
- Add support to sort - Ascending / Descending

* Added debug flag to Timeline support