Replace list of languages with map.

- Use ISO codes as keys for voice languages instead of enumeration.
- Instead of trying to select a suitable voicefile language from the UI
  language use the ISO codes stored as UI language and match against the
  mapping.
- Always store the selected UI language. Fixes the voicefile creation
  language lookup to fail if the language used is the system language.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@29207 a1c6a512-1295-4272-9138-f99709370657
6 files changed