Add explicit uint8_t casts for Blake2's key length.
via @evoskuil
Do not remove previously generated files from the distribution.
Merge branch 'master' of github.com:jedisct1/libsodium

* 'master' of github.com:jedisct1/libsodium:
  Add explicit uint8_t casts for Blake2's key length. via @evoskuil
Initial import of scrypt
scrypt fixes