1.9.0

CHANGES:

• Add seq, a testable for Seq.t and contramap (#412 @xvw)
• Expose the V1.Skip exception (#415, #416, @Khady)
• BREAKING FIX: match_raises now expects the user-defined function to return
  true for expected exceptions. Previously false was interpreted as an
  expected exception. (#418, #419, @psafont)