Continue new platform/glium implementations

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

raidillon_glium/src/system.rs

@@ -0,0 +1,35 @@
+use std::collections::HashMap;
+use raidillon_core::Scene;
+use glium::Surface;
+
+pub struct RenderingContext<'a, S: Surface> {
+    pub scene: &'a mut Scene,
+    pub target: &'a mut S,
+}
+
+/// The internal "rendering system" trait of raidillon_glium.
+/// This is unrelated to the main System trait in raidillon_core.
+pub trait RenderingSystem {
+    fn render<S: Surface>(ctx: &mut RenderingContext<S>);
+}
+
+type SystemID = String;
+
+pub struct RenderingSystemManager<T: RenderingSystem> {
+    pub systems: HashMap<SystemID, Box<T>>,
+}
+
+impl<T: RenderingSystem> RenderingSystemManager<T> {
+    pub fn new() -> Self {
+        Self {
+            systems: HashMap::new(),
+        }
+    }
+    pub fn add_system(&mut self, id: SystemID, system: T) {
+        self.systems.insert(id, Box::new(system));
+    }
+
+    pub fn remove_system(&mut self, id: SystemID) {
+        self.systems.remove(&id);
+    }
+}