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.
the same but shorter:
`content().match(function() { return typeof this.ctx.content === 'undefined'; })({ elem : 'control' });`