OpenImageIO 2.1.11.0

Release 2.1.11 (1 Feb 2020) -- compared to 2.1.10

• Python bindings for ParamValueList.attribute(), when being passed
  attributes containing multiple values, now can have those values passed
  as Python lists and numpy arrays (previously they had to be tuples).
  #2437
• OpenEXR support is extended to handle float vector metadata. #2459
• Developer goody: simd.h vfloat3 has added a normalize(), length(),
  and length2() methods, to more closely match the syntax of Imath::Vec3f.
  #2437
• Internals: changed a lot of assertions to only happen in debug build mode,
  and changed a lot that happen in release builds to only print the error
  but not force a termination. #2435
• simd.h fix errors in vbool == and !=. #2463
• Make sure the embedded 'farmhash' implementation is completely hidden
  behind proper namespaces. #2473
• Many docs fixes.