Clarify Section 7.3 * Acknowledge the fact that the context map is conceptually really a two-dimensional matrix with 2 different keys, but in reality stored as a one-dimensional array.
Clarify Section 7.3
* Acknowledge the fact that the context map is conceptually really a
two-dimensional matrix with 2 different keys, but in reality stored
as a one-dimensional array.

* Mention that InverseMoveToFrontTransform will not cause the
context map to have invalid indexes. This gives someone implementing
a decoder sanity that they do not have to go through the context
map again and check that all values are less than NTREES.

nicksay/brotli,smourier/brotli,smourier/brotli,nicksay/brotli,google/brotli,nicksay/brotli,smourier/brotli,anthrotype/brotli,google/brotli,google/brotli,smourier/brotli,google/brotli,szabadka/brotli,szabadka/brotli,google/brotli,szabadka/brotli,minhlongdo/brotli,google/brotli,anthrotype/brotli,nicksay/brotli,anthrotype/brotli,nicksay/brotli,anthrotype/brotli,google/brotli,anthrotype/brotli,google/brotli,minhlongdo/brotli,szabadka/brotli,smourier/brotli,minhlongdo/brotli,minhlongdo/brotli,nicksay/brotli,nicksay/brotli