bug#6085: Eshell doesn't handle ANSI escapes/colors well

[Ken Hori <fplemma@gmail.com>]

From Emacs bzr HEAD:

Eshell doesn't handle a terminal escape code like ^[.

My eshell-output-filter-functions:
 '(eshell-output-filter-functions (quote (eshell-handle-ansi-color
eshell-handle-control-codes eshell-watch-for-password-prompt
eshell-postoutput-scroll-to-bottom)))

Example:
[~/emacs.20100501/lisp/eshell]$ export TERM=xterm-256color
[~/emacs.20100501/lisp/eshell]$ *grep --color=auto ansi esh-*
^[[Kesh-mode.el^[[K^[[K:^[[K    eshell-handle-^[[Kansi^[[K-color
^[[Kesh-mode.el^[[K^[[K:^[[K(autoload
'^[[Kansi^[[K-color-apply-on-region "^[[Kansi^[[K-color")
^[[Kesh-mode.el^[[K^[[K:^[[K(defun eshell-handle-^[[Kansi^[[K-color ()
^[[Kesh-mode.el^[[K^[[K:^[[K  (^[[Kansi^[[K-color-apply-on-region
eshell-last-output-start
^[[Kesh-mode.el^[[K^[[K:^[[K		   'eshell-handle-^[[Kansi^[[K-color)
^[[Kesh-var.el^[[K^[[K:^[[K;; is identical to just saying (lisp); but
with the variable exp^[[Kansi^[[Kon


`term-handle-ansi-escape' from term.el seems to be be handling
ansi escapes very well. Maybe we can integrate  a modified
version of it into Eshell.