Remove the dual_clock watch face

I don't use this and it saves us some space due to the font

wasp/apps/faces.py

@@ -26,7 +26,6 @@ class FacesApp():
         choices.append(('clock', 'Clock'))
         choices.append(('week_clock', 'WeekClock'))
         choices.append(('chrono', 'Chrono'))
-        choices.append(('dual_clock', 'DualClock'))
         choices.append(('fibonacci_clock', 'FibonacciClock'))
 
         self.choices = choices

wasp/boards/manifest_240x240.py

@@ -7,7 +7,6 @@ manifest = (
     'apps/calc.py',
     'apps/clock.py',
     'apps/chrono.py',
-    'apps/dual_clock.py',
     'apps/faces.py',
     'apps/fibonacci_clock.py',
     'apps/flashlight.py',
@@ -26,7 +25,6 @@ manifest = (
     'apps/SleepTk.py',
     'fonts/__init__.py',
     'fonts/clock.py',
-    'fonts/clock_dual.py',
     'fonts/sans18.py',
     'fonts/sans24.py',
     'fonts/sans28.py',