Includes a number of changes, some more significant than others.

(I apologize for the big CL, I should have been committing and pushing these incrementally.)

1. PitchExtractor now also returns the strength of the pitch candidate, not just the hertz value.

2. The Villing Syllabifier has updated default parameters.  This leads to a much more accurate syllabification routine.

3. ContourFeatureExtractor no longer also includes region- or context-normalized features.  These need to be registered and extracted separately.

4. The 'contour' features -- pitch, intensity, etc. -- used to be cut down to size before being attached to each region.  This made extracting temporally based windows of features challenging, and in some cases impossible.  Now each point in a region contains a pointer to the full region, and each feature extractor is responsible for cutting to the right sized window.  (There might be some efficiency to be gained by caching previously constructed subregions, but this may be more trouble than it's worth.)  This change is the source of many of the changes in this CL.

Just a heads up.  The next significant update will be a move away from the current feature registry system.  This is a fairly significant source of memory bloat and ugly code.  I'm still playing with a few different ways of handling this, but feature extraction will still be driven by feature names.