Slideshow + frame animation

A widget (does not @bind anything) that takes an array of objects and displays them in a slideshow:

Slideshow([md"# Hey!", image_1, image_2])

with extra options to auto-advance (setting it to delay = 1/30 will make it an animation :)).

For example:

functions = [sin, cos, tan]

map(plot, functions)

gives an array of three plots, but it would be cool of you could do

Slideshow(map(plot, functions))

and click through the plots using buttons.

These should also work in the exported HTML.

Sizing of the slideshow box might be tricky