Add properties for button pressed state

Author: sebromero

src/modulino/buttons.py

@@ -165,4 +165,16 @@ def update(self):
     return button_states_changed
 
   def is_pressed(self, index):
-    return self._current_buttons_status[index]
+    return self._current_buttons_status[index]
+  
+  @property
+  def button_a_pressed(self):
+    return self.is_pressed(0)
+  
+  @property
+  def button_b_pressed(self):
+    return self.is_pressed(1)
+  
+  @property
+  def button_c_pressed(self):
+    return self.is_pressed(2)