Upgrades

Switch “animating” indicator class to “velocity-animating”. Closes #194.

Support for passing hex values into color properties. (Previously, you
could only pass in individual RGBA components.) Closes #179.

Fixes bug where slide functions wouldn’t reset elements’ height to
auto. Closes #183.

Support for getting border-color in Firefox. Closes #196.

Fixes inability to animate `y2` on SVG elements. Closes #199.

Allow passing in explicit `display: none` into an Out UI pack
transition. Closes #201.

Fixes vw/vh unit support for `translateX/Y`. Closes #181.

Fixes bug where `delay` couldn’t be used with `stagger`. Closes #202.
Thank you, @guanche.

Fixes bug where original call’s easing type wouldn’t be re-used for a
`reverse` command.