bug#2650: Add "lisp/term/screen.el" to support GNU Screen's 256 colors mode

[Prestoo Ten]

Please consider adding the file "lisp/term/screen.el" with the
following contents to support GNU Screen's "screen-256color" terminal
type:

(load "term/xterm")

(defun terminal-init-screen ()
    "Terminal initialization function for screen."
    ;; Use the xterm color initialization code.
    (xterm-register-default-colors)
    (tty-set-up-initial-frame-faces))

See discussion in the following threads on the emacs-devel mailing list:

http://article.gmane.org/gmane.emacs.devel/87582/
http://article.gmane.org/gmane.emacs.devel/109504/