Use full to construct 1-D NumPy array (#83)

* Use `full` to construct 1-D NumPy array

In `labeled_comprehension`, instead of using `empty` and assigning
`default_1d` the `default` value, simply use `numpy.full` to construct
the `default_1d` array with the `default` value.

* Drop blank line

As these are both arguments being passed into `labeled_comprehension`,
simply group them together.

dask_image/ndmeasure/__init__.py

@@ -285,9 +285,7 @@ def labeled_comprehension(input,
     )
 
     out_dtype = numpy.dtype(out_dtype)
-
-    default_1d = numpy.empty((1,), dtype=out_dtype)
-    default_1d[0] = default
+    default_1d = numpy.full((1,), default, dtype=out_dtype)
 
     pass_positions = bool(pass_positions)