generic_token_spans: whoops, make use of offsets
Fix type error (sigh!)

I miss Haskell.
Filtering P out from text should now superfluous
Remove stray RST context
RST minor cleanup
RST_DT: same paragraph/sentence

Approximated using not-that-great segmentation in original text
RST DT: compress whitespace in extracted feature text
rst-dt-util tmp: mostly useful for development
More doc update