Atomgroup removal (MDAnalysis#2562)

* Completes MDAnalysis#1070 and moves us towards v1.0 MDAnalysis#2443
* Removed AtomGroup stubs.
* Removed unnecessary import from groups.py
* Removes deprecation test
* Update CHANGELOG

package/CHANGELOG

@@ -86,6 +86,7 @@ Enhancements
   * Improve the distance search in water bridge analysis with capped_distance (PR #2480)
 
 Changes
+  * Removed AtomGroup stubs (PR #1070, Issue #2443).
   * encore.hes() doesn't accept the details keyword anymore, it always returns
     the relevant details instead, consistently with ces() and dres(), in the
     form of a dictionary (Issue #2465)

package/MDAnalysis/core/__init__.py

@@ -55,4 +55,3 @@
 
 from . import groups
 from . import selection
-from . import AtomGroup

package/MDAnalysis/core/groups.py

@@ -100,8 +100,6 @@
 import os
 import warnings
 
-from numpy.lib.utils import deprecate
-
 from .. import _ANCHOR_UNIVERSES, _CONVERTERS
 from ..lib import util
 from ..lib.util import cached, warn_if_not_unique, unique_int_1d

testsuite/MDAnalysisTests/core/test_atomgroup.py

@@ -56,12 +56,6 @@
 import pytest
 
 
-class TestDeprecationWarnings(object):
-    def test_AtomGroupUniverse_usage_warning(self):
-        with pytest.deprecated_call():
-            mda.core.AtomGroup.Universe(PSF, DCD)
-
-
 class TestAtomGroupToTopology(object):
     """Test the conversion of AtomGroup to TopologyObjects"""
     @pytest.fixture()