consolidate imports

src/scene.rs

@@ -1,11 +1,9 @@
+use gfx;
+use na;
+use piston;
 use view;
 use vr;
 
-extern crate gfx;
-extern crate gfx_device_gl;
-extern crate nalgebra as na;
-extern crate piston_window;
-
 pub trait Scene<D: gfx::Device,
                 F: gfx::Factory<D::Resources>> {
   fn event(&mut self, event: Event);
@@ -24,5 +22,5 @@ pub trait Scene<D: gfx::Device,
 
 pub enum Event {
   Vr(vr::Event),
-  Piston(piston_window::Input),
+  Piston(piston::input::Input),
 }