(Re)move autotools generated files from the repository.

(Re)move autotools generated files from the repository.

Ref: http://lists.gnu.org/archive/html/emacs-devel/2011-03/msg00225.html

* autogen/: New directory, to be excluded from releases.
* autogen/copy_autogen, autogen/update_autogen: New scripts.
* autogen/README: New file.
* autogen/aclocal.m4, autogen/config.in, autogen/configure:
* autogen/Makefile.in: Add auto-updated generated files.

* autogen.sh: No longer a no-op, now it tests for autotools
and runs them as necessary.

* configure.in: Defaule maintainer-mode to on.

* aclocal.m4, configure, lib/Makefile.in: Remove files.

* src/config.in: Remove file.

* INSTALL.BZR, admin/make-tarball.txt: Update instructions.