improve abstract property support (closes #11610)

Thanks to Darren Dale for patch.
diff --git a/Misc/ACKS b/Misc/ACKS
index c74b811..e47d738 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -220,6 +220,7 @@
 Antonio Cuni
 Brian Curtin
 Lisandro Dalcin
+Darren Dale
 Andrew Dalke
 Lars Damerow
 Evan Dandrea
diff --git a/Misc/NEWS b/Misc/NEWS
index cd9b061..ddf15a0 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -416,6 +416,8 @@
 Library
 -------
 
+- Issue #11610: Introduce a more general way to declare abstract properties.
+
 - Issue #13591: A bug in importlib has been fixed that caused import_module
   to load a module twice.