Allow empty array as default value when framing
Revert "Rely on newline character at the end of a toRdf test"

This reverts commit 7f768b15c359a4454334eaac79cd78d2c7981804. The test suite is inconsistent in that regard, see https://github.com/json-ld/json-ld.org/commit/8da1bb79677f9dc9f39e64af993c110fedba6b3b#commitcomment-3370674
Add support for @base: null

Ignore toRdf-0100-in.jsonld for the time being. See https://github.com/json-ld/json-ld.org/commit/177b5041c9fc145d84ddb307b8f11c86c805fca2#commitcomment-3374027