Electron applications in Rust

It's 2020, and a lot has changed.

With the advent of Webpack 5, the previous issues with using WASM in Electron have been vanquished. I can only assume some form of sorcery was involved. All examples have been updated to use the new version.
wasm32-unknown-unknown targets are enabled for stable Rust, everything updated to 2018 edition
The previous percy example has been removed. While work continues on the project, there haven't been any releases.
binaryen has been removed.
A new framework seed as been added as an example.
The stdweb example has been freshened up:
- Use #[wasm_bindgen(start)] to remove the app loader script
- Don't use innerHTML, just set the text content directly.

Each app is a starter example, and can be run with yarn install && yarn start.