Merge from emacs-24; up to r107984
In the Package Menu, indicate packages that are newly-available.

* lisp/emacs-lisp/package.el (list-packages): Compute a list of
packages that are newly-available since the last list-packages
invocation.
(package-menu--new-package-list): New var.
(package-menu--generate, package-menu--print-info)
(package-menu--status-predicate, package-menu-mark-install):
Handle new status label "new".
Standardize some more license notices
* lisp/emacs-lisp/package.el (package-installed-p): Warn if not ready.
* lisp/emacs-lisp/package.el (package-generate-autoloads): Kill buffer
"PKGNAME-autoloads.el" in case we created it.
* emacs-lisp/package.el (package-untar-buffer): Handle problematic tarfile content listings.
* emacs-lisp/package.el (package-untar-buffer): Improve integrity check for tarball contents.
Update copyright notices for 2013.