CDS-574, CDS-589, CDS-600 and CDS-601

rules for four new journals: npjcompumats, npjgenmed, npjregenmend and
npjscilearn
CDS-605 subjects for npjregenmed
CDS-580 and CDS-581 information for two pubserv test journals
Schematron changes

1. Use "ext-link" instead of "uri", so that links will work
2. Report two "year" elements in a citation (incorrect text), as these
will cause transform failures
Tagging Instructions change

Added a new chapter "Additional information for specific article types":
1. new information on Books and Arts (book and film reviews etc).
2. moved information on Protocols to this chapter
Merge pull request #26 from nature/release_0_15

Release 0 15