support spelled-out currencies

[patch]

Add support for spelled-out currencies using the unitPattern and displayName with a count attribute. For example, 5000 JPY (Japanese Yen) in ja (Japanese) would be 5,000 円 (as opposed to ￥5,000), which uses the unitPattern {0} {1} and displayName 円 with the count other. See UTS #35, Part 3, §4: Currencies for details.

Review the ICU API for this feature and determine what attribute should be used to enable it. Also consider how to best store and load the data because it will take much more memory than the other currency data.

This feature has been requested by users.