title: convert 2D numpy array of arrays to 3D array
body: <p>I would like to convert a 2D np.array of np.arrays into a 3D np.array.</p>
  
  <p>I have a 2D numpy array (A) with A.shape = (x,y)</p>
  
  <p>Each cell within A contains a unique 1D numpy array with A[0][0].shape = (z)</p>
  
  <p>I would like to convert A to a 3D numpy array with newA.shape = (x,y,z)</p>