Changes from 2.18.0 to 2.19.0

• New b2nd_expand_dims() function for expanding the dimensions of a b2nd array.
  This is useful for adding new dimensions to an existing b2nd array, e.g.,
  when you want to add a new dimension to a 2D array to make it 3D.
  Thanks to @lshaw8317 for the PR (#666 and #667).

• New internal view object that allows accessing the data in a b2nd array
  without copying it. The new b2nd_expand_dims() function makes use of this.
  In the future, it can also be useful for implementing e.g. a view on a slice
  of a b2nd array.