* lisp/emacs-lisp/package.el (package-alist): Include obsolete packages.
(package-obsolete-list): Remove.
(package-activate): Remove min-version argument. Add `force' argument.
Adjust to new package-alist format.
(package-mark-obsolete): Remove.
(package-unpack): Force reload of the package's autoloads.
(package-installed-p): Check builtins if the installed package is not
recent enough.
(package-initialize): Don't reset package-obsolete-list.
Don't specify which package version to activate.
(package-process-define-package, describe-package-1)
(package-menu--generate): Adjust to new package-alist format.