Don't copy per version anti features to all versions

make_v0() modified the apps data structure to copy an anti feature for a
specific version to all versions resulting in index-v1 and -v2 to
contain wrong anti feature annotations. This patch fixes this and adds a
test that the data structure is no longer modified.

The bug shadowed bugs in the AF implementation of -v1 and -v2 resulting
in not coping the version specific data. This is corrected as well.
This is also tested now.

For -v2 the AF dict is now sorted to make the result reproducible.

Finally The NoSourceSince AF was added as a per version and overall AF
in -v1 and is now only applied as an overall AF and the test is updated
accordingly.

tests/index.TestCase

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 
+import copy
 import datetime
 import inspect
 import logging
@@ -425,6 +426,7 @@ class IndexTest(unittest.TestCase):
         app['icon'] = 'info.zwanenburg.caffeinetile.4.xml'
         app['CurrentVersionCode'] = 4
         apps = {app.id: app}
+        orig_apps = copy.deepcopy(apps)
         apk = {
             'hash': 'dbbdd7deadb038862f426b71efe4a64df8c3edf25d669e935f349510e16f65db',
             'hashType': 'sha256',
@@ -436,7 +438,7 @@ class IndexTest(unittest.TestCase):
                 '-1': 'res/drawable/ic_coffee_on.xml',
             },
             'icons': {'160': 'info.zwanenburg.caffeinetile.4.xml'},
-            'antiFeatures': [],
+            'antiFeatures': ['KnownVuln'],
             'packageName': 'info.zwanenburg.caffeinetile',
             'versionCode': 4,
             'name': 'Caffeine Tile',
@@ -463,6 +465,7 @@ class IndexTest(unittest.TestCase):
             )
         )
         self.assertTrue(os.path.exists(os.path.join('repo', 'index.xml')))
+        self.assertEqual(orig_apps, apps, "apps was modified when building the index")
 
     def test_v0_invalid_config_exception(self):
         """Index v0 needs additional config values when using --nosign