v0.7

CHANGES:

• Fixed HMAC on BLAKE2{S,B} (@emillon)
• Fixed convenient_of_hex (@dinosaure, @hannesm, @cfcs)
• Add of_raw_string/to_raw_string (@samoht)
• Test digestif on solo5 and xen backends (@amoht)
• breaking change, commont type t is an abstract type
• Fixed META file (@dinosaure, @g2p)
• New dependency eqaf (@dinosaure, @cfcs, @hannesm) (constant-time equal function)
• Remove Obj.magic in common implementation (@dinosaure, @samoht)
• Add conveniences functions in common implementation (@hcarty)
• Add option-returning functions in common implementation (@harcty)
• Verify length of string on of_raw_string function (@hcarty)
• Release runtime lock (@andersfugmann, @dinosaure, @cfcs)
• Bounds check (@cfcs, @dinosaure)
• Fixed linking problem (@andersfugmann, @g2p, @dinosaure)
• Update OPAM file (@dinosaure)