Create textarea as separate block (close #1033)

I've made only basics yet: `common`+`desktop`, `BEMHTML`-templates, js, styles only for `islands` theme.
I didn't remove `input_type_textarea` to have ability to compare new block with it.
I don't see "graceful" degradation.
We should either add a polyfill for IE9 or remove this attribute until we're supporting IE9.  Otherwise we're creating precedent of inconsistent behaviour in the library.