The sectionId for each SentenceSegmentation is now set properly.

The SentenceSegmentation class has a sectionId field that is supposed
to contain the UUID of the SentenceSegmentation instance's enclosing
Section - but sectionId was not being set to any value.
tokenizationId is now set to tokenization.uuid instead of parse.uuid

The s2chelper() function was passing the Parse UUID to
extractTokenRefSequence(), instead of passing the Tokenization's UUID.