Add testing, rollup (ES modules, UMD, CJS), remove examples and webpack

[bencmbrook]

• Incorporates @jimmywarting's new tests 209 new test for reading and writing #53
• Incorporates Test fix #54 - tests passing across Safari, Chrome, Firefox, Edge!
• Native TransformStream support when it's available, else ponyfill
• Adds support for ES modules, UMD, and CommonJS
• Adds module to JSDelivr + Unpkg
• Switches Karma preprocessing from webpack to rollup
• Removes our examples directory
• Fixes benchmarking
• Updates docs

Issues fixed:

• Fixes ReadableStream.prototype.pipeTo's first argument must be a WritableStream #64
• Fixes Can't get to read entries data: [object Object] (Ponyfill issue) #63
• Fixes Benchmark demo not working? #61
• Fixes TransformStream ponyfill should only be used when necessary #52
• Fixes Error during install if we don't have yarn #59
• Closes Write some test #3

I'd suggest merging this directly to master and closing PRs #54 and #53.

This comes with a version bump to 3.0.0