wallpaper crate docs

This Rust library gets and sets the desktop wallpaper/background.

The supported desktops supported are as follows: * Windows * macOS * GNOME * KDE * Cinnamon * Unity * Budgie * XFCE * LXDE * MATE * Deepin * i3 (set only)

Example

```rust extern crate wallpaper;

fn main() { println!("{:?}", wallpaper::get()); wallpaper::setfromurl("https://source.unsplash.com/random").unwrap(); println!("{:?}", wallpaper::get()); } ```