Reactive draw mode

[parasyte]

The GUI currently redraws every frame at the display's refresh rate (e.g. 180 fps on my 180 Hz monitor). Even if there are no changes between frames.

We can easily switch to a reactive mode by only redrawing when egui requests it:

cartunes/src/framework.rs

Lines 150 to 155 in 2a3b989

	// End the egui frame and create all paint jobs to prepare for rendering.
	// TODO: Handle output.needs_repaint to avoid game-mode continuous redraws.
	let (output, paint_commands) = self.egui_ctx.end_frame();
	self.egui_state
	.handle_output(window, &self.egui_ctx, output);
	self.paint_jobs = self.egui_ctx.tessellate(paint_commands);