Massively reorganize and clean up the whole Rust codebase (#478)

* Massively reorganize and clean up the whole Rust codebase

* Additional changes during code review

editor/src/communication/message_handler.rs

@@ -0,0 +1,22 @@
+pub use crate::communication::dispatcher::*;
+pub use crate::input::InputPreprocessorMessageHandler;
+use crate::message_prelude::*;
+
+use std::collections::VecDeque;
+
+pub type ActionList = Vec<Vec<MessageDiscriminant>>;
+
+// TODO: Add Send + Sync requirement
+// Use something like rw locks for synchronization
+pub trait MessageHandlerData {}
+
+pub trait MessageHandler<A: ToDiscriminant, T>
+where
+	A::Discriminant: AsMessage,
+	<A::Discriminant as TransitiveChild>::TopParent: TransitiveChild<Parent = <A::Discriminant as TransitiveChild>::TopParent, TopParent = <A::Discriminant as TransitiveChild>::TopParent> + AsMessage,
+{
+	/// Return true if the Action is consumed.
+	fn process_action(&mut self, action: A, data: T, responses: &mut VecDeque<Message>);
+
+	fn actions(&self) -> ActionList;
+}