upgrade dev dependencies

[zakandrewking]

• fixes security warning with webpack-dev-server:

https://github.com/zakandrewking/escher/network/alert/package.json/webpack-dev-server/open

• good opportunity to add peer dependencies and create an unbundled npm build
• could also upgrade bundled dependencies, e.g. d3 libraries
• Need to consider these new warnings:

WARNING in configuration
The 'mode' option has not been set, webpack will fallback to 'production' for this value. Set 'mode' option to 'development' or 'production' to enable defaults for each environment.
You can also set it to 'none' to disable any default behavior. Learn more: https://webpack.js.org/concepts/mode/

WARNING in asset size limit: The following asset(s) exceed the recommended size limit (244 KiB).
This can impact web performance.
Assets:
  escher.js (1.07 MiB)
  escher.min.js (500 KiB)

WARNING in entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (244 KiB). This can impact web performance.
Entrypoints:
  escher (1.07 MiB)
      escher.js
  escher.min (500 KiB)
      escher.min.js


WARNING in webpack performance recommendations:
You can limit the size of your bundles by using import() or require.ensure to lazy load some parts of your application.
For more info visit https://webpack.js.org/guides/code-splitting/