Update records with import function: Add uitype 4 fields (record numbering field) to the mapping options.

When you want to update existing records it would be very useful to be able to select the id of the record as anchor.

You can select for example "Lead Number" as the duplicate criteria:

But in the mapping step you can't select that one as a mapping field:

See here for more context: http://vtiger-crm.2324883.n4.nabble.com/Vtigercrm-developers-How-to-import-and-overwrite-data-without-changing-record-IDs-td23209.html