events: implement a first attempt at an eventing system

src/buffers.rs

@@ -1,3 +1,4 @@
+use crate::events::{Event, EventBus};
 use crate::geometry::*;
 use crate::lib8::interpolate::Fract8Ops;
 use crate::power::AsMilliwatts;
@@ -235,7 +236,7 @@ impl Surfaces for BufferedSurfacePool {
 
 
 impl Task for BufferedSurfacePool {
-    fn tick(&mut self) {
+    fn tick(&mut self, event: &Event, bus: &mut EventBus) {
         if self.pool.read().unwrap().is_dirty() {
             self.pool.write().unwrap().commit();
         }