egui-modal, a modal library for egui

usage:

```rust let modal = Modal::new(ctx, "my_modal");

// What goes inside the modal modal.show(|ui| { modal.title(ui, "My modal"); modal.body(ui, "This is a modal"); modal.buttons(ui, |ui| { // After clicking, the modal is automatically closed if modal.button("A button").clicked() { println!("Hello world!") }; }); });

if ui.button("Open the modal").clicked() { // Show the modal modal.open(); } ```