[Feature request] keep track of edits required between two strings

[angusfong]

While calculating edit distance of two strings, could you possibly extend the library to keep track of the insertions, deletions, and replacements required to turn one string into another?

Eg. 'abcde' -> 'aacdde' we acquire something like

{'insertions': {4:'d'}, 'replacements': {1:'a'}}

or something similar?

This would be a great way to do error analysis of character error rates and similar metrics.