Effect swirl is now shown with clock.

include/effect_twirl.h

@@ -12,6 +12,8 @@ private:
     double _real_center_y = LED_HEIGHT / 2;
 public:
     void loop();
+    boolean can_be_shown_with_clock() override;
+    boolean clock_as_mask() override;
 };
 
 #endif

src/effect_twirl.cpp

@@ -1,6 +1,9 @@
 #include "effect_twirl.h"
 #include "functions.h"
 
+boolean TwirlEffect::can_be_shown_with_clock() { return true; };
+boolean TwirlEffect::clock_as_mask() { return true; };
+
 void TwirlEffect::loop() {
 	double center_x = _real_center_x; // - (cos8(_center_offset_angle)>>6);
     double center_y = _real_center_y; // + (sin8(_center_offset_angle)>>6);