macOS: Implement NSTextInputClient (#518)

Fixes #263

src/platform/linux/mod.rs

@@ -310,6 +310,14 @@ impl Window {
         }
     }
 
+    #[inline]
+    pub fn set_ime_spot(&self, x: i32, y: i32) {
+        match self {
+            &Window::X(ref w) => w.send_xim_spot(x as i16, y as i16),
+            &Window::Wayland(_) => (),
+        }
+    }
+
     #[inline]
     pub fn get_current_monitor(&self) -> RootMonitorId {
         match self {