Update trellis accessors for debugging

adafruit_neotrellis/multitrellis.py

@@ -131,10 +131,17 @@ def color(self, x, y, color):
         pad = self._key_pads[y][x]
         pad.pixels[pad.key_index(x, y)] = color
 
+    @property
+    def data_pending(self) -> bool:
+        for py in range(self._rows):
+            for px in range(self._cols):
+                available = self._trelli[py][px].count
+                if available > 0:
+                    return True
+        return False
+
     def sync(self):
         """Read all trellis boards in the matrix and call any callbacks"""
-        for _n in range(self._rows):
-            for _m in range(self._cols):
-
-                _t = self._trelli[_n][_m]
-                _t.sync()
+        for py in range(self._rows):
+            for px in range(self._cols):
+                self._trelli[py][px].sync()

adafruit_neotrellis/neotrellis.py

@@ -113,6 +113,9 @@ def sync(self):
                     ):
                         self.callbacks[evt.number](evt)
 
+    def local_key_index(self, x, y):
+        return int(y * self.width + x)
+
     def key_index(self, x, y):
         return int((y - self.y_base) * self.width + (x - self.x_base))