Wayland cursor implementation using `Waybackend` as the backend
This crate was make by adapting the code in `wayland-cursor-rs`, from the
`smithay` project.
Key differences:
- we do not allow automatically setting cursor fallbacks. You'd have to do
something manually every time
- when loading a cursor, you must pass closures for running the wayland
specific code. There are examples of how to do this in the documentation
**NOTE**: despite `waybackend` being a `#![no-std]` crate, `waybackend-cursor`
depends on std because of `xcursor-rs`.