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
Treat reverse term definitions more like regular definitions
Disallow blank nodes as data types
Blank node identifiers in N-Quads can begin with a digit as well

The grammar is still overly restrictive and should be improved.
Do not include nodes without any properties in flattened output
Do not create nodes for (data)types when creating the node map
Convert "partial" lists from RDF to JSON-LD
Do not produce generalized RDF by default
CS fixes
CS fix
Update README as suggested by @jneubert.

This closes #36.
Drop triples containing relative IRIs when converting to RDF

Graph using a relative IRI as graph name are dropped as well.
Allow context documents and context definitions in context parameter

This commit doesn't add support for it to the expandContext option yet.

The test manifest has been updated to include options in the meantime, thus
[ci skip]
Use options from test manifests and use correct URL in EARL reports
Expand the expandContext option to the full path in the TestManifestIterator

to simplify testing.

The produceGeneralizeRDF flag uses a different capitalization in the test manifest and thus one test currently fails. It will be fixed in the next commit, thus, for the moment
[ci skip]
The default value of useNativeTypes has been changed to false

Even with useNativeTypes set to false, strings will not be typed with xsd:string.

For the moment, both produceGeneralizedRdf and produceGeneralizedRDF are accepted as flag names for the toRDF algorithm. See https://github.com/json-ld/json-ld.org/commit/d6460dcef6fa207302e5d3912a44fdffd603669f#commitcomment-4015838
Bugfix: Clone test options before modifying them
Bugfix: Ensure that all lists of lists are detected

Previously lists which were contained in an array within a list weren't detected. For example:

    {
      "http://example.com/prop": {
        "@list": [ { "@list": [ 1, 2, 3 ] } ]
      }
    }

was considered to be a valid document.
Fix CS