README: Add jQuery environment notes
Docs: Link to the browser support page in CONTRIBUTING.md

Instead of duplicating the supported browsers matrix, just link to
the browser support page on jquery.com.
Effects: First step() call should match :animated selector

Fixes #14623
Closes gh-1473
Build: Happy New Year! Thanks @marlonlandaverde
Intro: Pass window to intro if available, for browserify

Closes gh-1476
Tests: Remove html5 shiv
Release: Publish to npm

Closes gh-1479
Authors: Update AUTHORS.txt and .mailmap
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