where we'd get multiple entries for copy-fields

unique - this is so that uri_ids in the public data repository can just use the values
which Stash has given them.

mapped licence

license from the root item if they don't have their own.
Also made the script detect the Commonwealth spelling "licence" and throw
an error with a message, rather than fail silently.

a slightly hacky special filter to control whether non-root datasets are
indexed.

and resolving items are unified. Have rejigged filtering and the filter
tests are passing. Added a test case for empty filters which let everything
through.

arrays and strings. Arrays are now the defaults for most of the tests.

of regexps and exact matches

filters the json-ld graph based on exact and regexp matches

to a solr record

integrate solr object creation into library

Closes rdm#930

See merge request !1