Add extraction for release dates for the new-format (at least) ninjatune xls files

Mostly putting up for review for the sake of this being a way to have people able to question my stuff and learn about the codebase.

This parses out the release dates in the newer of the two ninjatune xls formats (the old one has strings, as I recall, and I'm not sure it splits by country -- I haven't checked yet).
As a noob reading this I think what made the file somewhat hard to read was all the lambdas and asterisks everywhere. Is there a reason this can't be a named function that all the Rules share? (Another confusing thing was having to look for any tiny differences that might exist between the lambdas, but they actually turned out to be the same).