Add command to check all the exercises

This allows for skipping repeating "next" when multiple exercises
are done at once, or when earlier exercises have been updated/changed
(and thus must be redone) while still working of the whole set (i.e.
the final check_all is not yet available to flag those undone exercises)

src/watch/state.rs

@@ -195,6 +195,11 @@ impl<'a> WatchState<'a> {
         stdout.queue(ResetColor)?;
         stdout.write_all(b":list / ")?;
 
+        stdout.queue(SetAttribute(Attribute::Bold))?;
+        stdout.write_all(b"c")?;
+        stdout.queue(ResetColor)?;
+        stdout.write_all(b":check all / ")?;
+
         stdout.queue(SetAttribute(Attribute::Bold))?;
         stdout.write_all(b"x")?;
         stdout.queue(ResetColor)?;
@@ -274,6 +279,23 @@ impl<'a> WatchState<'a> {
         Ok(())
     }
 
+    pub fn check_all_exercises(&mut self, stdout: &mut StdoutLock) -> Result<ExercisesProgress> {
+        stdout.write_all(b"\n")?;
+
+        if let Some(first_fail) = self.app_state.check_all_exercises(stdout, false)? {
+            // Only change exercise if the current one is done...
+            if self.app_state.current_exercise().done {
+                self.app_state.set_current_exercise_ind(first_fail)?;
+            }
+            // ...but always pretend it's a "new" anyway because that refreshes
+            // the display
+            Ok(ExercisesProgress::NewPending)
+        } else {
+            self.app_state.render_final_message(stdout)?;
+            Ok(ExercisesProgress::AllDone)
+        }
+    }
+
     pub fn update_term_width(&mut self, width: u16, stdout: &mut StdoutLock) -> io::Result<()> {
         if self.term_width != width {
             self.term_width = width;

src/watch/terminal_event.rs

@@ -11,6 +11,7 @@ pub enum InputEvent {
     Run,
     Hint,
     List,
+    CheckAll,
     Reset,
     Quit,
 }
@@ -37,6 +38,7 @@ pub fn terminal_event_handler(
                     KeyCode::Char('r') if manual_run => InputEvent::Run,
                     KeyCode::Char('h') => InputEvent::Hint,
                     KeyCode::Char('l') => break WatchEvent::Input(InputEvent::List),
+                    KeyCode::Char('c') => InputEvent::CheckAll,
                     KeyCode::Char('x') => {
                         if sender.send(WatchEvent::Input(InputEvent::Reset)).is_err() {
                             return;