Add features and start writing interfaces

engine/src/audio_engine/mod.rs

@@ -6,7 +6,7 @@ trait AudioBackend {
     // It should be executed either on the startup,
     // or when the audio backend is switched
     fn start_client();
-    // Initialization of the client should happen 
+    // Initialization of the client should happen
     // when a project is opened.
     fn init_client();
 }