Flags are not accurate

[nicobo]

Find a more accurate flag or representation : currently flags are based on ISO 3361, which is for country codes.
This is different from language ; for instance Hebrew is supported by Watson as he (it seems to be a code from ISO 639) but :HE: is not a country code in ISO 3361.

See :

• Add emoji flags to languages jmsv/ety-python#30
• http://www.flagsarenotlanguages.com/blog/why-flags-do-not-represent-language/
• https://github.com/10xjs/locale-emoji
• https://github.com/unicode-cldr/cldr-core/blob/master/supplemental/likelySubtags.json
• https://unicode.org/reports/tr35/#Likely_Subtags
• http://cldr.unicode.org/index/cldr-spec/language-tag-equivalences