ext/sodium: avoid tautological comparisons

ext/sodium: signing empty messages is fine

ext/sodium: avoid negations on unsigned values

ext/sodium: throw an exception if only the prefix of a hex string is valid

Improve sodium "invalid parameters" error messages

Fix a few places where ZPP throw got reverted to ZPP

Fix symbol name

ext/sodium: the second parameter of sodium_hex2bin() is optional

ext/sodium: AI_StringRef_And_String -> AI_StringRefAndString for consistency

Fix constant references in error messages in ext/sodium

sodium ext: if it's a length, call it "length"!

sodium ext: add bindings for sodium_pad() and sodium_unpad()

sodium ext: restore sodium_remove_param_values_from_backtrace() call

sodium ext: sync sodium_crypto_kdf_derive_from_key() with the standalone ext

Use libsodium's native function if available, use correct constant names
in error messages

sodium ext: Constants were renamed SODIUM_*
Adjust error messages accordingly.

sodium ext: If sodium_init() returns 1, this is fine.

We actually want to do this so that multiple extensions using libsodium
can be loaded simultaneously.

Remove param values from backtrace in exception thrown from ZPP throw

Change zend_parse_parameters() to zend_parse_parameters_throw() in ext/sodium

sodium ext: Use _ietf_ vs _IETF_ consistently

sodium ext: No need for #ifdef crypto_aead_chacha20poly1305_IETF_

chacha20poly1305_ietf was implemented in libsodium 1.0.4 which is way earlier
than the minimum version we support.

Sodium ext: Isolate a return statement for consistency

sodium ext: The default password hashing function is not supposed to be Argon2i

sodium ext: long -> zend_long

sodium ext: Add missing "return" statements after zend_throw_exception()

sodium ext: skip scrypt if it is not available

scrypt was removed from minimal libsodium builds in version 1.0.13