Typescale mixin

[gillesbertaux]

We could add a typescale mixin maybe, I drafted sth quickly to get the essence of it, it won't work but you get the idea:

// el-width == you width element (e.g div)
// bp == breakpoint, the idea is to add as many as wanted
// $bp1 = width of breakpoint
@mixin type-scale($el-width, $bps: ($bp1, $bp2, $bp3)) {
  $each $bp in $bps {
    $bp/$el-width : $scaled;
    font-size: $scaled + rem; 
  }
}

What do you guys think?