Fixed copy/paste bugs:
- Protocol 3 does not support alpha.
- Protocol 1 does not use 8+8 bits per X/Y coordinate.
Improved description:
- Convert introduction to bullet-points.
- Simplified headers for better links.
- Added example with calculations to protocol 0.
- Moved "Only supported ..." messages below header (in bold).
- Describe protocols in terms of one another.