load_layout! macro for loading layout from XML for egui

The load_layout! macro allows for loading layout configurations from XML for use with the egui GUI framework. It takes an XML representation of the layout structure and generates Rust code to construct the layout within an egui UI.

Example

use eframe::egui;
use egui::{Rounding, Ui};
use egui_xml::load_layout;

struct MyApp;

fn color_background(ui: &mut Ui, color: egui::Color32) {
    ui.painter()
        .rect_filled(ui.available_rect_before_wrap(), Rounding::same(5.0), color);
}

impl eframe::App for MyApp {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        egui::CentralPanel::default().show(ctx, |ui| {
            load_layout!(
                <Strip direction="west">
                    <Panel size="relative" value="0.3">
                        color_background(ui, egui::Color32::from_rgb(0, 0, 255));
                    </Panel>
                    <Panel size="remainder">
                        <Strip direction="north">
                            <Panel size="relative" value="0.3">
                                color_background(ui, egui::Color32::from_rgb(0, 255, 255));
                            </Panel>
                            <Panel size="remainder">
                                color_background(ui, egui::Color32::from_rgb(255, 0, 255));
                            </Panel>
                        </Strip>
                    </Panel>
                </Strip>
            );
        });
    }
}