PR#44976 by David H. Gutteridge.
This module implements the Wagner-Fischer dynamic programming
technique, used here to calculate the edit distance of two strings.
The edit distance is a measure of the degree of proximity between two
strings, based on "edits": the operations of substitutions, deletions
or insertions needed to transform the string into the other one (and
vice versa). The module is designed to be easily extensible by
functioning as a base class for other modules.
