* helm.el: Improve multi key feature (Thanks Michael Heerdeg).
(helm-make-multi-command): new
(helm-define-multi-key): Use it.
(helm-multi-key-defun): new.
(helm-toggle-resplit-and-swap-windows): New multikey function.
(helm-map): Bound it to C-t.
* helm-elisp.el (helm-multi-lisp-complete-at-point): New multikey function.
* helm-config.el: font lock `helm-multi-key-defun'.
* helm-buffers.el (helm-buffer-match-major-mode): Fix search with ^name @inside pattern.