SIngle WASM instance, memory set up by JS

This is an educational project, the app itself have no practical value (except if you're planning to buy a Chevy Volt, and not sure about the color). Features:

• Simple compilation on all major platforms (GNU/Linux, MacOS, Windows10)
• Demonstrates calls JS->WASM, WASM->JS
• JS and WASM use common memory
• Verbose JS loader (sould be shorter, but this version shows all the WASM interface elements)

Thanks for contributors, see PRs!