Implement language extension proposal to support attributes on a language level.

[nikita-leonov]

Sample of extension proposal: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1370.pdf

[nikita-leonov]

I think we will need to start from building an initiative group of members of various companies. I will start to work on establishment relationship with LLVM. We will need to check is it possible or not to get Apple in.