DDSXTY15 — Need to ignore unspecified ranges

There can be a difference between versions of the XTypes spec supported by different vendors. For example, one vendor could support XTypes 1.4 (where the unit/range annotations are incorporated in the meta-data) and another vendor might be using the XTypes 1.3 version (where the unit/range annotations were not incorporated in the meta-data).

In order to ignore the effects this has on units, the XTypes1.4 spec has a new attribute called ignore_unspecified_units, which defaults to TRUE. However, there is no similar field to ignore_unspecified_ranges. This may cause the two vendors to ignore one-another based on the fact that they don't agree on how to deal with the difference in ranges.