- Use tao::tuple instead of FunctionInterface to hold array/portal
  collections.
- Type signatures are simplified. Now just use:
  - ArrayHandleCompositeVector<ArrayT1, ArrayT2, ...>
  - make_ArrayHandleCompositeVector(array1, array2, ...)
  instead of relying on helper structs to determine types.
- No longer support component selection from an input array. All
  input arrays must have the same ValueType (See ArrayHandleSwizzle
  and ArrayHandleExtractComponent as the replacements for these
  usecases.