Single ownership, move semantics, and a new memory layout

This MR drastically changes the way Inko works, how memory is managed, the memory layout, etc. It's too much to cover in this MR, instead I'll cover it in the release notes. But in short: Inko will use a form of single ownership like Rust, but a more flexible version of it. For concurrency we're borrowing some ideas from Pony, but again in a more flexible/accessible manner.