Deprecate 'crop' in CDORemapper() and add variable 'crop_domain' for automatically generating 'crop'

Deprecate 'crop' in CDORemapper(). It is automatically assigned as the borders of lat/lon selectors in Start() call. (WIP)

Revise the checks for depending dimension list names; Add explanation of how to use values() to define dependency relation.

Stop if merge_across_dims and split_multiselected_dims are both used but this file dim selector is multi-dim array

Fix the time unit attribute retrieval if the format is YYYY-M-D. Also, split_multiselected_dims is changed to FALSE if it is useless.