Each cipher module's random() now returns a thread-local Random that is
created on first use and reused thereafter. Each thread gets its own
OS-seeded generator (own key+nonce), so no locking and no cross-thread
nonce collisions. random_key() and random_nonce() draw from this CSPRNG
instead of secrets.token_bytes, making them as fast as the stream.
Changes made in the aegis256x4.py template and regenerated.
