Now support Haxe 3.
Seperate i18n run-time methods to Global class, to fix Haxe 3 compile-sequence issue.
Add onChange macro method, for handling run-time locale changes.
Changed I18n.str() to I18n.i18n(), I18n.res() to I18n.i18nRes(), for better readability when using 'using' mixin.
Merge branch 'master' of https://github.com/rockswang/i18n