Deprecate high level API and only convert evdev events

[dogtopus]

Turns out it's way too complicated and slow to do all the high level event emission ourselves. Plus that there's better, more battle-tested event sequencers like evemu, it makes having our own event sequencer an even worse idea.

Maybe we should pivot from making a fully featured gamepad emulator to just a simple event converter for evdev devices. This way it would also make ffsds4 more useful as a gamepad converter which will be more useful to an end-user for example.