input.Makefile: Mapping: Support multiple segments of a source table flat file. Use with_cat_csv if flat file segment(s) are available; otherwise use the input file in $+ or the input database, if any. Don't look for an explicit CSV header file because it can now be handled as the first segment if appropriately named.
input.Makefile: Mapping: Support multiple segments of a source table flat file. Use with_cat_csv if flat file segment(s) are available; otherwise use the input file in $+ or the input database, if any. Don't look for an explicit CSV header file because it can now be handled as the first segment if appropriately named.