Correctly handle multiple "selected" elements

[fregante]

Having multiple items in view, especially with contain: true, has two unwanted behaviors:

1. Flickity lets you click from 1 to 2, but nothing happens (caused by contain)
2. There's a selected class, but it only applies to one element (always happens)

You can see both here:

Test case: https://codepen.io/anon/pen/dddYvZ

Sadly I had to switch to iDangerous Swiper because it behaves how I want (for 2 it still applies one class, but it never reaches the end, so .active + .slide + .slide lets me select the last visible slide). Its demo http://idangero.us/swiper/demos/110-slides-per-view.html

[desandro]

Thanks for reporting this issue. See #289 (comment)