SDK / exoplayer

Also add missing file.

- Adds support for dash manifests that define SegmentTemplate
  but no SegmentTimeline.
- Assumes that the device clock is correct when calculating which
  segments to load. The final step here is to use the Utc timing
  element in the DASH manifest to obtain an accurate client clock.
- Doesn't yet enforce that the client shouldn't load segments that
  are in the future or behind the live window.

This wasn't actually used for anything other than showing a
toast, which is now generated based on the manifest instead.

Issue: #200

dev -> dev-hls

Also update gradle files.

Github issue: #183

dev -> dev-hls

This fixes the referenced issue, except that the MPD parser
needs to actually parse out UUID and binary data for schemes
that we wish to support. Alternatively, it's easy to applications
to do this themselves by extending the parser and overriding
the parseContentProtection and buildContentProtection methods.

Github Issue: #119

It's cleaner to not inject data into the extractor only
so that it can be read out as though it were parsed from
the stream. This is also an incremental step towards
fixing Github issue #119.

Add SPS/PPS to the media format.

dev -> dev-hls

Issue: 186

Issue: 186

Note: This adds support for the majority of DASH live streams,
however we do not yet correctly support live streams that rely
on UtcTimingElements in their manifests.

Issue: #52

Plus start to properly document the SmoothStreaming package.
Note that where the documentation is a little vague, this is
because the original SmoothStreaming documentation is equally
vague!

- Split sample pools for video/audio/misc, since the typical
  required sample sizes are very different (and so it becomes
  inefficient to use a sample sized for video to hold audio).
- Add TODO for further improvements.

Issue: #174

dev -> dev-hls

The timestamp scaling in SegmentBase.getSegmentTimeUs was
overflowing for some streams. Apply a similar trick to that
applied in the SmoothStreaming case to fix it.

- Move all three buffering constants to a single class (the
  chunk source).
- Increase the target buffer to 40s for increased robustness
  against temporary network blips.
- Make values configurable via the chunk source constructor.
- Treat captions as a text track for HLS. This allows them to
  be enabled/disabled through the demo app UI.

Issue: #165

- Add options to switch abruptly at segment boundaries. Third
  parties who guarantee keyframes at the start of segments will
  want this, because it makes switching more efficient and hence
  rebuffering less likely.
- Switch quality faster when performing a splicing switch (when
  we detect that we need to switch variant, we now immediately
  request the same segment as we did last time for the new variant,
  rather than requesting one more segment for the old variant
  before doing this.