Update scrollLeft in response to 'scroll' event

[nilclass]

Fixes #171

Previously the glider dots were not updated when scrolling. Also when dragging after scrolling, the scroll offset would jump back to where it was before the scrolling as soon as the drag started.

I believe the bug was introduced by the changes in #146. Oddly those changes don't seem to be part of the minified file on current master (search for scrollLeft - it only shows up as .ele.scrollLeft), which is why the problem does not appear in the demos.

[nilclass]

The only real change is this line. The hunks below were changed by the linter.

[NickPiscitelli]

Nice catch. This looks good and makes sense to me, but I'm wondering if the assignment should just be placed in updateControls instead. While the naming convention isn't the most semantic since the function appears to do more than actually update the controls, it's already setting a few other core values such as slide and page.

[nilclass]

Thanks for taking a look at the changes!

but I'm wondering if the assignment should just be placed in updateControls instead.

To be honest, I haven't fully grasped why both _.scrollLeft and _.ele.scrollLeft are needed. So I can't really judge if it breaks anything to set _.scrollLeft in updateControls.