OCW cannot handle data on curvilinear coordinates - needs to be improved

The current OCW cannot handle data on curvilinear coordinates. The problem occurs in "dataset.spatial_bounaries". This module checks the spatial boundaries of input (both reference and target) datasets. The checking process fails when the input long/lat are in 2-d arrays (or it works only when the input long/lat are in 1-d arrays). This limitation prevents processing the regional model data from the NASA downscaling project on map projected domains.