- Add details about the VP8L chunk support.
- Also add new example bitsteams containing VP8L chunk.
- Add back a section describing the VP8 chunk.
- Restrict some fields to 16 or 24 bits instead of 32 bits.
- Fields whose values are always positive are stored 1-based
instead of 0-based.
- Unknown chunks can only occur at certain places in the file.
- Remove the restriction for some fields to be divisible by 32 or 16.
Instead they are restricted to be even.
- Add a restriction for (canvas_width * canvas_height) product.
- Add 3 bits for rotation & symmetry in VP8X flags.
- Add some new example layouts.
- Add/clarify some nitty-gritties throughout the doc.
- Use the terms frame/tile more consistently and logically.
- Update related TODOs.
Change-Id: I611c1f58ecc3ee87546ca31bad1609376fad251e
