Marc mapping upgraded to support richer set of operations, including subfields, multiple fields in one line (separated by comma), and the removal of rules, e.g. -245 at the start of a line. A Marc to Qualified Dublin Core crosswalk from the Library of congress has been added as "etc/marc2qdc.txt". A collection can then choose to, for example, top up the mapping with its own version of the file stored in its local "etc" folder, specifying only the rules that are different. This is where a rule like "-245" might be used to override a more general rule from the main file that has all subfields in 245 mapping to one metadata item (Title). If the user specifies a different different filename -- through a plugin option -- then they are free to divise a mapping from scratch and store it in the collections local "etc" folder.
