v0.21.9 release with L.CRS.Simple projection and related fixes to _cornerExceedsMapLats()

[jywarren]

Release re: #1007

First release since #742

• Push dragend event to overlay Push dragend event to overlay #1014
• Multiple changes re: MapKnitter Lite: fetch images from Internet Archive MapKnitter Lite: fetch images from Internet Archive #998
• changed in DistortableImage.Keymapper- by removing the function changed in DistortableImage.Keymapper- by removing the function #783
• Removed function keyword from setMode, nextMode methods and updated t… Removed function keyword from setMode, nextMode methods and updated t… #766
• Conversions to ES6, from Convert to ES6 #372

Process

(this is a list from publiclab/image-sequencer#2089 so we'll need to adapt it)

• open an issue using the "release" template with this checklist with title Checklist and coordination for v0.0.0 major/minor/patch release (see semantic versioning)
• compile release notes
• open a pull request with updated version numbers
  • update version number in package.json (ex #1695)
  • run npm install to update package-lock.json
  • check in package-lock.json
• finalize and merge to main branch (freeze merges to main branch until next step)

We don't use a stable branch here, though we could later:

Now, move to `stable` branch:

* [ ] force push from `main` to `stable`

• publish stable branch to npm with npm publish (logging in first as necessary)

Draft a release:

• create a release on GitHub and use features description + release notes from below
• tag version number branch (i.e. v0.0.0) based on stable or choose stable
• publish to live Github pages demo (from within GitPod works well)
• move anything necessary to next release project, i.e.
• close this issue!

[gitpod-io]

[jywarren]

This needs to be published next!

[jywarren]

Published as v0.21.9 - https://www.npmjs.com/package/leaflet-distortableimage

[jywarren]

Small fix in #1141 as well; will be v0.21.10