ryg_rans is not a library

Fabian Giesen's ryg_rans, a 2014 rANS coding example, is not meant for production use. It's a toy implementation to illustrate algorithm ideas, not a robust or optimized library. Giesen advises against using its static byte model, alias table variant, or SIMD interleaving in real bitstreams. He recommends implicit interleaving with two states, 32-bit or 64-bit state with appropriate renormalization, and adaptive exponential-moving-average models for practical rANS implementations.