Timer App (#355)

* built timer app

* Style improvements

* making sure buttons stay hidden when the app is reopened and reappear after the timer runs out

* more sensible calculations of time deltas. eliminated that mysterious scaling factor

* changing the timer icon

src/displayapp/screens/Timer.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include "Screen.h"
+#include "components/datetime/DateTimeController.h"
+#include "systemtask/SystemTask.h"
+#include "../LittleVgl.h"
+
+#include "components/timer/TimerController.h"
+
+namespace Pinetime::Applications::Screens {
+  
+  
+  class Timer : public Screen {
+  public:
+    
+    enum class Modes {
+      Normal, Done
+    };
+    
+    Timer(DisplayApp* app, Controllers::TimerController& timerController);
+    
+    ~Timer() override;
+    
+    bool Refresh() override;
+    
+    void setDone();
+    
+    void OnButtonEvent(lv_obj_t* obj, lv_event_t event);
+  
+  private:
+    
+    bool running;
+    uint8_t secondsToSet = 0;
+    uint8_t minutesToSet = 0;
+    Controllers::TimerController& timerController;
+    
+    void createButtons();
+    
+    lv_obj_t* time, * msecTime, * btnPlayPause, * txtPlayPause, * btnMinutesUp, * btnMinutesDown, * btnSecondsUp, * btnSecondsDown, * txtMUp,
+        * txtMDown, * txtSUp, * txtSDown;
+  };
+}