refactor view/scene to separate modules

src/scene.rs

@@ -0,0 +1,15 @@
+use view;
+
+extern crate gfx;
+extern crate gfx_device_gl;
+extern crate piston_window;
+
+pub trait Scene<D: gfx::Device,
+                F: gfx::Factory<D::Resources>> {
+  fn update(&mut self);
+  fn render(&self,
+            factory: &mut F,
+            encoder: &mut gfx::Encoder<D::Resources, D::CommandBuffer>,
+            target: &gfx::handle::RenderTargetView<D::Resources, view::ColorFormat>,
+            depth: &gfx::handle::DepthStencilView<D::Resources, view::DepthFormat>);
+}