Fix hidden.bs.tooltip and shown.bs.tooltip events firing too early in tooltip.js

* events fire only after the CSS animation is completed
* this fixes also events in popover.js (as it inherits from tooltip.js)
carousel: correctly reset when the slide event is prevented
Pass $element to offset top/bottom calc funcs

At the moment to make dynamic top offset calculator on multiple elements, one would write:

``` javascript
$('.my-affix').each(function () {
  var $el = $(this);
  $el.affix({
    offset: {
      top: function () { return $el.offset().top; }
    }
  });
})
```

This patch will allow to:

``` javascript
$('.my-affix').affix({
  offset: {
    top: function ($el) { return $el.offset().top; }
  }
});
```
don't create new Tooltip/Popover objects just to destroy them immediately
Add 'collapse' class back after expanding
Only preventDefault on click on [data-toggle="modal"] when the element is a link

In it's current state Bootstrap always prevents the default action for a click
event on `[data-toggle="modal"]` elements
(see https://github.com/twbs/bootstrap/blob/master/js/modal.js#L233).
Instead this should only happen when the element is a link.
removed outline from modal
Customizable backdrop opacity
Added opacity to customizer and rebuilt customizer
Adding contextual styles to list-items
Active state overrides contextual list-item styles
Options of sizes added in modal
Adjust in modal size rules
Scrollspy acting up when targets are hidden

If elements are hidden using `display: none;` which are targets mapped by scrollspy, the plugin might select an incorrect or no menu item.

Checking if the target is visible solved this.
Add well-border variable

Add a variable to allow the well border color to be specified.

The reason I'd like to see this included is that my companies styleguide
requires an explicit border color on well-like constructs. This variable
allows me to easily override the default to use that color.
docs derp
Merge branch 'master' into docs_derp

Conflicts:
	dist/css/bootstrap.min.css
Update affix properly on scrollspy speedy scroll to top of page #11310

Fix scrollspy.js so as affix is updated properly when user scrolls fast
to top of page.

A fix for issue #11310.
Carousel: Use the transition duration from CSS

This makes it possible to change the transition duration in CSS
Fix #11400 and #11431