__getitem__ uses self._n instead of self._buf // 4

- self._buf would be incorrect if there are headers
- adafruit#9

Author: margaret

adafruit_dotstar.py

@@ -162,7 +162,7 @@ def __setitem__(self, index, val):
     def __getitem__(self, index):
         if isinstance(index, slice):
             out = []
-            for in_i in range(*index.indices(len(self._buf) // 4)):
+            for in_i in range(*index.indices(self._n)):
                 out.append(
                     tuple(self._buf[in_i * 4 + (3 - i) + self.start_header_size] for i in range(3)))
             return out