title: Swiper-Slide-Active class when Swiper is multirow
body: <p>I have Swiper set to show 2 rows per column, but when I do this then the Swiper-Slide-Active class are not properly set, i.e. this class is not applied to the slides (2) that are shown in the center of the swiper.</p>
  
  <p>Any idea what am i doing wrong here?, settings for the swiper below:</p>
  
  <pre><code>var swiper = new Swiper('.swiper-container', {
                  pagination: '.swiper-pagination',
                  effect: 'coverflow',
                  grabCursor: true,
                  centeredSlides: true,
                  slidesPerView: 'auto',
                  slidesPerColumn: 2,
                  spaceBetween: 20,
                  simulateTouch: true,
                  centeredSlides:true,
                  slideToClickedSlide: true,
                  paginationClickable:true,
                  grabCursor:true,
                  coverflow: {
                      rotate: 45,
                      stretch: 0,
                      depth: 100,
                      modifier: 1,
                      slideShadows: false
                  }
              });
  </code></pre>