restored functionalitity for adding list.

got accidently lost

python/damask/_rotation.py

@@ -303,8 +303,16 @@ class Rotation:
 
 
     def append(self,other):
-        """Extend rotation array along first dimension with other array."""
-        return self.copy(rotation=np.vstack((self.quaternion,other.quaternion)))
+        """
+        Extend rotation array along first dimension with other array(s).
+
+        Parameters
+        ----------
+            other : Rotation or list of Rotations.
+
+        """
+        return self.copy(rotation=np.vstack(tuple(map(lambda x:x.quaternion,
+                                                      [self]+other if isinstance(other,list) else [self,other]))))
 
 
     def flatten(self,order = 'C'):

python/tests/test_Rotation.py

@@ -817,6 +817,14 @@ class TestRotation:
         print(f'append 2x {shape} --> {s.shape}')
         assert np.logical_and(s[0,...] == r[0,...], s[-1,...] == p[-1,...]).all()
 
+    @pytest.mark.parametrize('shape',[None,1,(1,),(4,2),(3,3,2)])
+    def test_append_list(self,shape):
+        r = Rotation.from_random(shape=shape)
+        p = Rotation.from_random(shape=shape)
+        s = r.append([r,p])
+        print(f'append 3x {shape} --> {s.shape}')
+        assert np.logical_and(s[0,...] == r[0,...], s[-1,...] == p[-1,...]).all()
+
     @pytest.mark.parametrize('quat,standardized',[
                                                   ([-1,0,0,0],[1,0,0,0]),
                                                   ([-0.5,-0.5,-0.5,-0.5],[0.5,0.5,0.5,0.5]),