* src/gcrypt.h.in (GCRY_CIPHER_SALSA20): New.
* cipher/salsa20.c: New.
* configure.ac (available_ciphers): Add Salsa20.
* cipher/cipher.c: Register Salsa20.
(cipher_setiv): Allow to divert an IV to a cipher module.
* src/cipher-proto.h (cipher_setiv_func_t): New.
(cipher_extra_spec): Add field setiv.
* src/cipher.h: Declare Salsa20 definitions.
* tests/basic.c (check_stream_cipher): New.
(check_stream_cipher_large_block): New.
(check_cipher_modes): Run new test functions.
(check_ciphers): Add simple test for Salsa20.