Stable version of Segmentation.praat

Some key functionality of this version of the Segmentation.praat script:

* Trial number, target word, and repetition number are added automatically for each trial;
* The segmenter can quit and resume segmenting;
* The script notifies the segmenter of consecutive trials of the same target word and automatically determines the correct suffix for the context labels of that trial's segmentations;
* Subjects with trial time-data and without trial time-data are treated the same, so the segmenter doesn't have to be trained on two different protocols.

Also included is an example of the SegmentationDirectories.praat file that will need to be edited to match the local filesystem from which Segmentation.praat is run.