Don't assume specific filenames in supplemental data

[srl295]

http://www.unicode.org/reports/tr35/#Supplemental_Data states this now, and the upcoming revision will hopefully make this even more clear: One should not assume any specific filenames used under supplemental, according to the LDML spec.

In other words, don't open dayPeriods.xml expecting day periods and only day periods, or supplementalData.xml expecting specific other data. Logically, you should open the entire supplemental data directory and merge the XML trees together, and use the resolved tree for access to supplemental data.

[GuySmithFerrier]

Thanks. I will resolve this in a future release.