Word edit distance reduce runtime and memory usage

[ogallagher]

• [ ] Make edit distances a single shared structure, rather than owned individually by each word. This might not actually reduce memory usage at all, because I still need to store the distance between every word a and b, bidirectionally. If the data structure is singular, each distance will still have n^2 keys (n = word count).

• [ ] Ignore edit distances beyond a configurable threshold. For the threshold, I can use the same formula as the configurable choice variance.

• [ ] Begin calculating edit distances while parsing the source text.

• Move word edit distances structure into storage as temp files? Maybe this is overkill, for a future enhancement. It may be better to move other structures into storage first, like the lists of sentences and words.

[ogallagher]

Consult this article on VSCode performance profiling for how to confirm worse offenders.

[ogallagher]

택시 운전사 대본 - 33쪽까지, Word.edit_distances instance member = 420MB