Adds 'inner_encoding' to ArrayType

Adds 'inner_encoding' attribute to ArrayType parameter type.  The attribute enables outbound (retrieval) conversion of the stored object-array into an ndarray who's datatype is indicated by inner_encoding.  Object and String data types are not converted.  If inner_encoding is None, the array is NOT converted,  this is the default.

Verified only for single-nested arrays (i.e. result in a 2d array).