habit face

Track a single habit, occuring at most once per day, with an eight-day
look back and total count

movement/movement_faces.h

@@ -74,6 +74,7 @@
 #include "morsecalc_face.h"
 #include "rpn_calculator_face.h"
 #include "ships_bell_face.h"
+#include "habit_face.h"
 // New includes go above this line.
 
 #endif // MOVEMENT_FACES_H_