join: Added map_1_core_only option that uses only columns 0 and 1 of map_1. This is useful for one-time refactoring joins where the Source column, mappings comments, etc. shouldn't be part of the datasource's via map (although they will be part of the autogenerated VegBIEN map)
join: Added map_1_core_only option that uses only columns 0 and 1 of map_1. This is useful for one-time refactoring joins where the Source column, mappings comments, etc. shouldn't be part of the datasource's via map (although they will be part of the autogenerated VegBIEN map)