Clean up InformationFragment.
Clean up resources.
Add new media playback icons.
Modularise video and annotation rendering.

- Playback happens in VideoPlayerFragment.
- Playback is controlled by VideoPlayerActivity.
- Annotations are handled by AnnotationRenderService.
- MarkerRenderer places native views onto a MarkerCanvas.
Implement pinch to zoom for videos.

Video is now drawn on a TextureView.
Replace FloatPosition with Android's PointF.
Move pinch to zoom into a custom ViewGroup.

Now uses GestureDetectors to detect zooming and panning.
Tweak subtitle style.
Fix marker canvas touch events.
Focus of scaling is now in the right place (in the center of the pinch
gesture)
Fix annotation position bound checking.
Clean up VideoPlayerFragment.
Add missing override annotation to MarkerCanvas.
Use new icons for playback controls.
Merge pull request #17 from learning-layers/feature/LL-715-and-LL-659

Annotations use native views, video playback modularised, can pinch to zoom.