Replace genfromtxt with loadtxt

This is much faster (it reduced the running time for the cifti2 tests from 51 seconds to 15 seconds on my computer). The main disadvantage of loadtxt is that it can not handle missing values, but there should be no missing values anyway

Author: MichielCottaar

nibabel/cifti2/parse_cifti2.py

@@ -517,28 +517,28 @@ def flush_chardata(self):
             # conversion to numpy array
             c = BytesIO(data.strip().encode('utf-8'))
             vertices = self.struct_state[-1]
-            vertices.extend(np.genfromtxt(c, dtype=np.int))
+            vertices.extend(np.loadtxt(c, dtype=np.int))
             c.close()
 
         elif self.write_to == 'VoxelIndices':
             # conversion to numpy array
             c = BytesIO(data.strip().encode('utf-8'))
             parent = self.struct_state[-1]
-            parent.voxel_indices_ijk.extend(np.genfromtxt(c, dtype=np.int).reshape(-1, 3))
+            parent.voxel_indices_ijk.extend(np.loadtxt(c, dtype=np.int).reshape(-1, 3))
             c.close()
 
         elif self.write_to == 'VertexIndices':
             # conversion to numpy array
             c = BytesIO(data.strip().encode('utf-8'))
             index = self.struct_state[-1]
-            index.extend(np.genfromtxt(c, dtype=np.int))
+            index.extend(np.loadtxt(c, dtype=np.int))
             c.close()
 
         elif self.write_to == 'TransformMatrix':
             # conversion to numpy array
             c = BytesIO(data.strip().encode('utf-8'))
             transform = self.struct_state[-1]
-            transform.matrix = np.genfromtxt(c, dtype=np.float)
+            transform.matrix = np.loadtxt(c, dtype=np.float)
             c.close()
 
         elif self.write_to == 'Label':