Stretch augmentation simplified via dseg search?

[Luke-Poeppel]

It seems that a far simpler solution to the current stretch_augment implementation in hash_table.py would be simplified by migrating this to rolling_hash_search and using the dseg (or retrograde of it). At that point, it would
probably be wise to implement the FragmentHashTable.get_by_ql_array that migrates the more complicated modification search methods (like subdivision, contiguous summation, etc.).

In this new implementation (some time after v1.0.0), I would do a simple dseg search and then run the calculation after the fact for tracking in the Extraction.