Make mouse::Button::Other take u16 instead of u8

On wayland keys correspond to <input-event-codes.h>,
and they are past the limit of u8, causing the
back and forward buttons to be 20 and 19 which definitely isn't right
(they should all be around 0x110..=0x117).

Author: bbb651

core/src/mouse/button.rs

@@ -11,5 +11,5 @@ pub enum Button {
     Middle,
 
     /// Some other button.
-    Other(u8),
+    Other(u16),
 }

winit/src/conversion.rs

@@ -250,7 +250,7 @@ pub fn mouse_button(mouse_button: winit::event::MouseButton) -> mouse::Button {
         winit::event::MouseButton::Right => mouse::Button::Right,
         winit::event::MouseButton::Middle => mouse::Button::Middle,
         winit::event::MouseButton::Other(other) => {
-            mouse::Button::Other(other as u8)
+            mouse::Button::Other(other)
         }
     }
 }