Make the terminal not appear on Window

[Rodrigodd]

In principle, we only need to add #![windows_subsystem = "windows"] to the crate root to make it not spawn a terminal. But this would also make it not attach to the terminal it is called from, which makes the CLI more clumsy.

Ideally, we should also distribute a .cmd shim that calls the main binary and attaches it to its terminal. There are a couple of ways of doing this (I only remember the one used in mpv, right now), and I need to find out which one is better/easier to implement.