wayland: Move initialization to the Rust side

This will help make the init procedure safer, by limiting the number of Rust objects that need to be carried to the C side and may be mangled on the way there.

The second benefit is that it allows outputs to become part of new state management.

src/event_loop/driver.rs

@@ -29,7 +29,9 @@ use std::time::Instant;
 use crate::logging::Warn;
 
 
+/// Type of the sender that waits for external events
 type Sender = mpsc::Sender<Event>;
+/// Type of the sender that waits for internal state changes
 type UISender = glib::Sender<Commands>;
 
 /// This loop driver spawns a new thread which updates the state in a loop,