Investigate simplifying the Converter interface.

[peterhuffer]

Determine whether the Converter interface would be more friendly to use if the available methods, fromAlpha2, fromAlpha3, and fromNumeric were simplified to a method that takes a country code's format value and the from and to standards. For example, Converter.fromFormatValue(String formatValue, Standard from, Standard to).

[rymach]

Also, it isn't obvious to users that although the converter interface will allow converting within the same standard, it won't actually work unless there is an entry in mappings.csv.

It may be worth ensuring conversion from alpha2 to alpha3 (or the opposite) within a standard also works through this interface instead of requiring users to traverse getStandardEntries.