added better error description on corpus.parse failure.
Use PICKLE to preserve parses

Big change! All files are pickled so that the second run is much faster
if they’ve not been changed.  Also removed recurse(direction=‘upward’)
which didn’t return results as wanted.  When fixed will have a
different name than recurse()
Fixed variable warning
fixed small errors that arose in singleProcessTest
Added naturalLanguageObjects

for David Perez
appen docs to last commit

(these should not be committing — changes???)
comment out tests for D Perez until it works.
Updated core corpus metadata bundle.
Optimized ChordReducer.

Reduced the number of tree traversals per reduction session.
Optimized ChordReducer.
Optimized ChordReducer.
Streamlined ChordReducer.
Optimized ChordReducer.
Streamlined ChordReducer.

ChordReducer now returns only its chord-wise results.
Tidied elvis_trecento demo.