Make source-map work in the browser

[hildjj]

To test:

rm -rf node_modules package-lock.json
npm install
npm run build
ls -l docs/vendor/peggy/peggy.min.js

Note that the size of peggy.min.js is ~110kB, NOT ~500kB.

Run a web server (I'll eventually add one to the project so this is easier), and visit development/test.html

What this patch does:

• Only uses source-map-generator in production. This avoids pulling in the wasm and JSON dependencies from source-map, which don't tree shake out and are not needed by the generator.
• Uses source-map 0.7 for testing
• Fixes up as many of the warnings as I could figure out from source-map requiring node modules like url, path, and fs, which aren't actually used in the tests
• Ensures that the source-map tests run in the browser by pointing SourceMapConsumer at its needed WASM file, served from GitHub. Ideally, we will bundle this as base64 into the test file, but that's a problem for another day.

[hildjj]

It also updates all of the other dependencies, since the eslint world is a mess at the moment.

[Mingun]

Thanks! Actually, I did the same things but forgot to run deploy scripts (on Windows this is not so easy as run npm run build ... because cp command is not working there).

I prefer to make a one commit for one purpose, so I've split transition to source-map-generator from the dependencies update. All your work in the source-map branch now, so I close this PR.