Calculate ABA-checkdigit

[Thorium]

I was thinking something like this, should NachaSharp do basic ABA-routing number verifications?

Questions:

• What to do if check fails? We don't want to kill the whole file-processing.
• I can't get the current master to compile, maybe because FSharp.Data.FlatFileMeta version issues or something.

[adamdecaf]

The Fed and most financial institutions will reject files that contain routing numbers which fail their checksum. When parsing you would need to parse the record enough to issue a R28 back to the originator.

[Thorium]

Good point. This was just original idea; I'm right now lucky enough to not be responsible of generating Nacha files, but something tells me I will run out of luck again at some point when working in finance.