Consider clarifying some of the carousel classes (right, left, icon-*)

Created by: petetnt

Similar to #18390 (closed), one thing that has bothered me for a long while are some of the Carousel-components classes:

The example from http://v4-alpha.getbootstrap.com/components/carousel/#example:

<div id="carousel-example-generic" class="carousel slide" data-ride="carousel">
  <ol class="carousel-indicators">
    <li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li>
    <li data-target="#carousel-example-generic" data-slide-to="1"></li>
    <li data-target="#carousel-example-generic" data-slide-to="2"></li>
  </ol>
  <div class="carousel-inner" role="listbox">
    <div class="carousel-item active">
      <img data-src="holder.js/900x500/auto/#777:#555/text:First slide" alt="First slide">
    </div>
    <div class="carousel-item">
      <img data-src="holder.js/900x500/auto/#666:#444/text:Second slide" alt="Second slide">
    </div>
    <div class="carousel-item">
      <img data-src="holder.js/900x500/auto/#555:#333/text:Third slide" alt="Third slide">
    </div>
  </div>
  <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">
    <span class="icon-prev" aria-hidden="true"></span>
    <span class="sr-only">Previous</span>
  </a>
  <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
    <span class="icon-next" aria-hidden="true"></span>
    <span class="sr-only">Next</span>
  </a>
</div>

The carousel-controls have utility class looking classes called .left and .right. Following the common naming pattern of Bootstrap, shouldn't these be carousel-control-left and carousel-control-right? Following the pattern could (should?) enable a clearer structure for the carousel-controls altogether (see: https://github.com/twbs/bootstrap/blob/v4-dev/scss/_carousel.scss#L89).
- The .left and .right classes are also trigger to animate carousel-item transitions. Not sure if these should be made into verbs? As in .sliding.left or something similar, like collapsing is.
Same for .icon-next and .icon-prev: they look like utility classes, but are are exclusive to the carousel component. Would carousel-icon carousel-icon-left/right or just .carousel-icon-left and .carousel-icon-right serve the purpose better?

Opinions?