Add HideApplication and QuitApplication key assignments

```
[[keys]]
key = "q"
mods = "CMD"
action = "QuitApplication"
```

refs: https://github.com/wez/wezterm/issues/150

docs/changelog.markdown

@@ -14,6 +14,11 @@ brief notes about them may accumulate here.
   size of new terminal windows
 * Added `hide_tab_bar_if_only_one_tab = true` config option to hide the tab
   bar when the window contains only a single tab.
+* Added `HideApplication` key action (defaults to `CMD-H` on macOS only) which
+  hides the wezterm application.  This is macOS specific.
+* Added `QuitApplication` key action which causes the gui loop to terminate
+  and the application to exit.  This is not bound by default, but you may
+  choose to assign it to something like `CMD-Q`.
 
 ### 20200202-181957-765184e5
 

src/config/keys.rs

@@ -38,6 +38,8 @@ impl std::convert::TryInto<KeyAssignment> for &Key {
             KeyAction::Copy => KeyAssignment::Copy,
             KeyAction::Paste => KeyAssignment::Paste,
             KeyAction::Hide => KeyAssignment::Hide,
+            KeyAction::HideApplication => KeyAssignment::HideApplication,
+            KeyAction::QuitApplication => KeyAssignment::QuitApplication,
             KeyAction::Show => KeyAssignment::Show,
             KeyAction::IncreaseFontSize => KeyAssignment::IncreaseFontSize,
             KeyAction::DecreaseFontSize => KeyAssignment::DecreaseFontSize,
@@ -103,6 +105,8 @@ pub enum KeyAction {
     SendString,
     Nop,
     Hide,
+    HideApplication,
+    QuitApplication,
     Show,
     CloseCurrentTab,
     ReloadConfiguration,

src/frontend/gui/termwindow.rs

@@ -1250,6 +1250,14 @@ impl TermWindow {
             MoveTabRelative(n) => self.move_tab_relative(*n)?,
             ScrollByPage(n) => self.scroll_by_page(*n)?,
             ShowTabNavigator => self.show_tab_navigator(),
+            HideApplication => {
+                let con = Connection::get().expect("call on gui thread");
+                con.hide_application();
+            }
+            QuitApplication => {
+                let con = Connection::get().expect("call on gui thread");
+                con.terminate_message_loop();
+            }
         };
         Ok(())
     }

src/keyassignment.rs

@@ -39,6 +39,8 @@ pub enum KeyAssignment {
     MoveTab(usize),
     ScrollByPage(isize),
     ShowTabNavigator,
+    HideApplication,
+    QuitApplication,
 }
 
 pub struct KeyMap(HashMap<(KeyCode, KeyModifiers), KeyAssignment>);
@@ -150,6 +152,9 @@ impl KeyMap {
             [KeyModifiers::ALT, KeyCode::Char('9'), ShowTabNavigator],
         );
 
+        #[cfg(target_os = "macos")]
+        m!([KeyModifiers::SUPER, KeyCode::Char('h'), HideApplication],);
+
         Self(map)
     }
 

window/src/connection.rs

@@ -28,6 +28,11 @@ pub trait ConnectionOps {
     fn terminate_message_loop(&self);
     fn run_message_loop(&self) -> Fallible<()>;
 
+    /// Hide the application.
+    /// This actions hides all of the windows of the application and switches
+    /// focus away from it.
+    fn hide_application(&self) {}
+
     // TODO: return a handle that can be used to cancel the timer
     fn schedule_timer<F: FnMut() + 'static>(&self, interval: std::time::Duration, callback: F);
 }

window/src/os/macos/connection.rs

@@ -85,6 +85,12 @@ impl ConnectionOps for Connection {
         Ok(())
     }
 
+    fn hide_application(&self) {
+        unsafe {
+            let () = msg_send![self.ns_app, hide: self.ns_app];
+        }
+    }
+
     fn schedule_timer<F: FnMut() + 'static>(&self, interval: std::time::Duration, callback: F) {
         let secs_f64 =
             (interval.as_secs() as f64) + (f64::from(interval.subsec_nanos()) / 1_000_000_000_f64);