Enums now support PEP 3155 fro Python v3.3 and later.
Eliminated all compiler warnings when building on Windows with qmake.
Updated the NEWS file.
Released as v4.16.3.
Added tag 4.16.3 for changeset 8ead57151bd1
Virtual handlers with handwritten code can no longer be considered to be the
same.
Added the AllowNone function annotation.
Implemented the /DisallowNone/ argument annotation.
Added the /DisallowNone/ function annotation.
Added the /AbortOnException/ function annotation.