Create _ast module.

Cleanup Python-ast.c generation.

Doc/lib/lib.tex

@@ -416,6 +416,7 @@ and how to embed it in other applications.
 \input{distutils}
 
 \input{compiler}                % compiler package
+\input{libast}
 
 \input{libmisc}                 % Miscellaneous Services
 \input{libformatter}