Add T_PYSSIZET in structmember.h: This can be used for
Py_ssize_t members.

Simplify the implementation of UnicodeError objects:
start and end attributes are now stored directly as
Py_ssize_t members, which simplifies various get and
set functions.
diff --git a/Misc/NEWS b/Misc/NEWS
index 97ebc89..6f2cf9d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -14,6 +14,8 @@
 
 - Patch #1733960: Allow T_LONGLONG to accept ints.
 
+- T_PYSSIZET can now be used in PyMemberDef lists for Py_ssize_t members.
+
 - Prevent expandtabs() on string and unicode objects from causing a segfault
   when a large width is passed on 32-bit platforms.
 
@@ -687,6 +689,9 @@
 - Fix utf-8-sig incremental decoder, which didn't recognise a BOM when the
   first chunk fed to the decoder started with a BOM, but was longer than 3 bytes.
 
+- The implementation of UnicodeError objects has been simplified (start and end
+  attributes are now stored directly as Py_ssize_t members).
+
 Extension Modules
 -----------------