- Simplified dropdown styles to no longer ship with upward or downward facing arrows attached to the dropdown menu.
- Dropdowns can be built with `<div>`s or `<ul>`s now.
- Rebuilt dropdown styles and markup to provide easy, built-in support for `<a>` and `<button>` based dropdown items.
+- Renamed `.divider` to `.dropdown-divider`.
- Dropdown items now require `.dropdown-item`.
- Dropdown toggles no longer require an explicit `<span class="caret"></span>`; this is now provided automatically via CSS's `::after` on `.dropdown-toggle`.