Philippe's enhancements to the PDTB stub
educe.stac.corenlp: create manifest dir if needed

Bit suspicious: why hasn't this come up before?
More helpful stac-util merge-dialogues msg
Change stac-util tmp to dialogue act renamer
Avoid confusingly named 'None' for pdtb annotator
educe.pdtb.corpus.mk_key

Create a corpus key from PDTB-relevant information
educe.rst_dt.corpus.mk_key: hide corpus key details
Touch up RST DT tutorial a bit (mk_key)
Flesh out the PDTB tutorial a bit more
api-doc for educe.pdtb.ptb