Update corenlp to version 3.4, XML output

CoreNLP 3.4 allows XML output in interactive mode,
so we use that instead of parsing the plain text output.
The existing corenlp_xml module does most of the hard work.
Fix xml interpretation for multiple sentences
Merge pull request #63 from vanatteveldt/corenlp_3.4_xml

Update corenlp to version 3.4, XML output