Build a proper slideshow component

[johndigital]

Using "scoped slots" is the way to do this: https://vuejs.org/v2/guide/components.html#Scoped-Slots

Add some documentation about gallery gravity effects, and add minimum styling.

[SaFrMo]

I started a branch called slideshow to work on this. Looks like Vue testing might not support scoped slots yet, so that's something to keep in mind!

[SaFrMo]

From Drew's wishlist at #22:

OK, here is my running list of things that are common for slideshows/galleries

• Work as a component or as a shortcode in wp-content
• Next/Prev divs
• Pagination indicator (either boxes or numbers)
• Video background, or image background
• Gravity on contents (probably just use CCS classes)
• Auto advance of slides
• Option to stop auto advance on click
• Ability to start at X index slide
• Ability to jump to X index slide
• Delay start of slide by X seconds (useful when showing multiple galleys on a page in a grid)
• Basic events (maybe not needed yet)
• Basic methods (maybe not needed yet)

[johndigital]

Version 1 of this is now implemented and documented in ba0ff2e. All of the above features are included!