Add script to check duplicate strings with different casing

[miafoo]

For example, we might have written "ZIP code" one place and "Zip code" another place. It would be nice to have a script finding errors like that so we can correct them and keep things consistent.

And maybe an option to compare against strings with matching contexts as well!

"This is a test" has 5 occurences (1 with context)

Bonus points for a general list of string similarities to catch strings which could be merged.