Fix haddock typo
Scrypt.Enc (packParams): redundant conversion
Fix pseudo code: the salt is 32 8-bit words, not 32 bits

The salt is 256 bits.
Properties: test that we can retrieve plain from decode
Scrypt.Enc (defaultMeta): use NUL rather than literal 0

Previously, the 0 was treated as a regular character.
Merge branches 'unnecessary-conversion', 'fix-nul', 'docfix', 'docs' and 'serialize-prop'