Timing Module Update

- Implement a new timing module
- Utilize the new timing module in glium platform implementation for frame limiting and fixed engine updates timing.

engine/src/system.rs

@@ -19,7 +19,8 @@ pub trait System {
     /// Spawn the first entities of the world.
     fn load_world(&mut self, _ctx: &mut SystemContext) {}
     fn handle_event(&mut self, _ctx: &mut SystemContext) {}
-    fn update(&mut self, _ctx: &mut SystemContext) {}
+    fn fixed_update(&mut self, _ctx: &mut SystemContext) {}
+    fn frame_update(&mut self, _ctx: &mut SystemContext) {}
 }
 
 pub struct SystemManager {