wip: Changes of the week

- Move engine to a different crate
- Add engine trait
- Refactor the rest of the codebase to work with these changes
- Add debug ui buffer, use it to finish imgui support

platform/src/platform.rs

@@ -1,9 +1,9 @@
 use raidillon_assets::ModelManager;
-use raidillon_core::Engine;
+use raidillon_core::engine::EngineTrait;
 use crate::PlatformContext;
 
-pub trait Platform {
+pub trait Platform<E: EngineTrait> {
     /// Initialize platform.
-    fn initialize(engine: Engine, title: String, width: u32, height: u32) -> Self;
+    fn initialize(engine: E, title: String, width: u32, height: u32) -> Self;
     fn run(self);
 }