[Examples] Merge the long awaited Examples sandbox

[beefchimi]

While there are still a few items that remain to be resolved, this PR is ready to merge into master. Merging this will resolve:

• Would this work with trello style lists? #4
• Provide playground examples #6
• Local setup guide #50
• [Feature Request] Source code for example gh-page #55
• Publish source code for project homepage? #62

I will spend the next few days making some tiny adjustments to it before hosting the dist files.

Tasks for Draggable

• OneAndOnly: [Beta.4] Height issue using mirror: {constrainDimensions: true}
• MultipleContainers: [Beta.4] Uncaught DOMException: Failed to execute 'insertBefore' on 'Node': The node before which the new node is to be inserted is not a child of this node.
• MultipleContainers: Why does evt.cancel() not work as expected?
• Floated: I'm having a hard time with the placed class and options... can we please chat about this?
• Collidable: Need to have the draggable-container--over class applied on initial pickup (if it is of course over the container... which, it should be?)
• Collidable: There should be a draggable-collidable--colliding class
• SwapAnimation: Cannot finish this until we support swapping on both the x and y axis.
• Draggable: Can you please add a watch task for work on the library? I want people to be able to develop both the library and the examples simultaneously.

Questions

• All: When dragging <a> tags on iOS, I often get a delay, and the contextual menu. Is there a fix for this?
• Lib: Should we be transpiling the library to ES5? Or should we instead ask the consumer to do it?
• Droppable: Do we expect to add the ability for "capacity" in Droppable? Or do we instead prefer to just ask consumers to use logic for a normal container to not accept more than x children?
• Collidable: I have an idea for Collidable... let's chat in person.
• Examples folder: Do we want to disable CI from looking at /examples?

Examples site

• Go over entire site for accessibility audit once accessibility is finished.
• Is the striped gradient wacky in other browsers?
• Finish MultipleContainers example.
• Eventually make the "slider puzzle" Restrict Axis example.
• Eventually make the Droppable capacity example.
• Would be nice to both stretch and squish the plates... but that could be a bit too tricky
• Rename all assets that might be cached by the landing page service worker
• Figure out a way to prevent the 2nd placed animation on release of Snappable... maybe a release modifier class?

[tsov]

🙏 ❤️

[fredbenenson]

Awesome!