adding getter setter properties for background_color

Author: FoamyGuy

adafruit_display_text/label.py

@@ -171,6 +171,19 @@ def color(self):
     def color(self, new_color):
         self.palette[1] = new_color
 
+    @property
+    def background_color(self):
+        """Color of the background as an RGB hex number."""
+        return self.palette[0]
+
+    @background_color.setter
+    def background_color(self, new_color):
+        if new_color:
+            self.palette[0] = new_color
+            self.palette.make_opaque(0)
+        else:
+            self.palette.make_transparent(0)
+
     @property
     def text(self):
         """Text to display."""