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