NJW (and other German law journals)

This style is based on the "Juristische Zitierweise (Stüber)" style by Oliver Wolf and Philipp Zumstein
    (https://www.zotero.org/styles/juristische-zitierweise), but the citation is adapted for the style of
    German law journals, such as NJW (Neue Juristische Wochenschrift), MMR (Multimedia und Recht) etc., as follows:
    - Citations are in-text. In German legal journals sometimes citations are used in footnotes, sometimes in-text,
      although the citation itself does not differ. With "in-text", you can choose for yourself and create the
      footnotes yourself using your word-processor if necessary.
    - Citations do not end with ".". The "." is obsolete for in-text citations. Furthermore, citations in German law
      journals are often accompanied by supplemental text and explanations.
    - Commentaries and handbooks should use publication type "entry-encyclopedia". See details below.
    - note that some law journals use slightly different citation
Changes after review

bibliography review comments have been disregarded for now. See comments in discussions.
renamed file
more changes after review
Renamed file
removed macro "edition-if-available" 

and other changes after review
Added new behaviour for legal commentaries ... 

using the fields series-editor and container-title
Changed to footnote style ...

and added reference to first citation in case of 2nd (or more) citation.
Update neue-juristische-wochenschrift.csl
deleted macro inbook, bugfixes
Merge pull request #1239 from rm2342/patch-1

NJW (and other German law journals)