Continue new platform/glium implementations

- Assets, asset manager system
- Rendering system trait
- Kick off glium platform implementation
- And more

raidillon_platform/src/platform.rs

@@ -1,5 +1,5 @@
-
 pub trait Platform {
     /// Initialize platform.
     fn initialize(title: String, width: u32, height: u32) -> Self;
+    fn run(self);
 }