function renaming and comment cleanup

[stuwest]

Internal and external function renaming ahead of addition of supplemental data:

• initialize_locale() -> initialize_locale_bucket()
• generalized $cache_key by removing localized-names-
• cldr_locale_bucket_file to cldr_locale_file
• get_localized_names() to get_locale_bucket()
• __() to get_cldr_item()
• _territory() to territory_name() (temporarily also leaving in _territory() for backward compatibility)
• _currency_symbol() to currency_symbol()
• _currency_name() to currency_name()
• _language() to language_name()

Also some comment and readme cleanup (including updating examples to use more complicated locales from GlotPress trunk)

addresses https://github.com/Automattic/wp-cldr/issues/32, https://github.com/Automattic/wp-cldr/issues/31, https://github.com/Automattic/wp-cldr/issues/30

[jblz]

:+1: good stuff