Upgrade gl, package.json, and travis node version

[rreusser]

The headless-gl version was very far behind so that finding a version of node with which it actually installs (not too old, not too new) is relatively difficult, package-lock.json was using the old style, and the version of node on travis was 6.

This PR makes some maintenance development upgrades which should not affect any runtime functionality. The goal is simply to reduce maintenance friction in order to keep the wheels turning a bit longer.

I observe a few failing tests when running locally, for what I presume are low-level bugs or breaking changes in node/gl/gpu driver APIs which have occurred sometime in the last few years. I think it would be wise to resolve these before publishing.

Edit: I tacked on a couple more fixes, including switching to github actions from travis as well as fixing and removing failing badges.

[rreusser]

Tests weren't running at all, so that can't be worse, and no runtime code is modified, so there should be no introduced breakages. I don't expect any reviewers to drop by (though anyone is welcome!), therefore I'm just going to get this merged with the hope that it makes maintenance 2% easier.