Full Languages Support with Built-in expressions

[Jeehut]

I read in the README that built-in support for expressions in more languages is planned / desirable. I want to create this issue as a TODO list for all languages iOS supports and open discussion about some changes that might be needed or suggested (if any) when new situations in other languages arise.

List of languages supported:

• English
• Chinese
• French
• German
• Italian
• Japanese
• Korean
• Spanish
• Arabic
• Catalan
• Croatian
• Czech
• Danish
• Dutch
• Finnish
• Greek
• Hebrew
• Hindi
• Hungarian
• Indonesian
• Malay
• Norwegian
• Polish
• Portuguese
• Romanian
• Russian
• Slovak
• Swedish
• Thai
• Turkish
• Ukrainian
• Vietnamese

Also here are some resources that might help when implementing this:
https://developer.mozilla.org/en-US/docs/Mozilla/Localization/Localization_and_Plurals
http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
http://localization-guide.readthedocs.org/en/latest/l10n/pluralforms.html