This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last three weeks. Most important changes:
* Added UTF8 context model for good text compression.
* Simplified context modeling by having only 4 context modes.
* Per-block context mode selection.
* Faster backward copying and bit reading functions.
* More efficient histogram coding.
* Streaming support for the decoder and encoder.
(1) Move all variable declarations to the beginning of the block.
(2) Remove 'z' printf modifiers.
(3) Fix 'comma at the end of enumeration list' warning.
Roderick Sheeter