Python function annotations removed from -py3 option.

Python function annotations containing C/C++ types are no longer
generated when using the -py3 option. Function annotations support
has been moved to a feature to provide finer grained control.
It can be turned on globally by adding:

  %feature("python:annotations", "c");

or by using the command line argument:

  -features python:annotations=c

The implementation is designed to be expandable to support different
annotations implementations. Future implementations could implement
something like the following for generating pure Python types:

  %feature("python:annotations", "python");

or typing module types to conform to PEP-484:

  %feature("python:annotations", "typing");

Closes #1561
Issue #735

CHANGES.current

@@ -7,6 +7,20 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-02-27: wsfulton
+            [Python] #735 #1561 Function annotations containing C/C++ types are no longer
+            generated when using the -py3 option. Function annotations support has been
+            moved to a feature to provide finer grained control. It can be turned on
+            globally by adding:
+
+              %feature("python:annotations", "c");
+
+            or by using the command line argument:
+
+              -features python:annotations=c
+
+            *** POTENTIAL INCOMPATIBILITY ***
+
 2022-02-26: wsfulton
             #655 #1840 Add new warning WARN_LANG_USING_NAME_DIFFERENT to warn when a
             method introduced by a using declaration in a derived class cannot