bug#15539: 24.3; setting user-emacs-directory at command line invocation

[Mike Carifio <carifio@carifio.org>]

-----------------------

I'd like a switch for the emacs command line, something like
--user-emacs-directory, that sets the user emacs directory on startup,
rather than hardcodes ~/.emacs.d/. So, for example:

  emacs --user-emacs-directory ~/mine.d/

Will look for the emacs init.el in ~/mine.d/init.el.

-----------------------




In GNU Emacs 24.3.1 (x86_64-pc-linux-gnu, GTK+ Version 3.6.4)
 of 2013-10-03 on louvi, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11303000
System Description:	Ubuntu 13.04

Configured using:
 `configure '--build' 'x86_64-linux-gnu' '--build' 'x86_64-linux-gnu'
 '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib'
 '--localstatedir=/var/lib' '--infodir=/usr/share/info'
 '--mandir=/usr/share/man' '--with-pop=yes'
 '--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.3/site-lisp:/usr/share/emacs/site-lisp'
 '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes'
 '--with-x-toolkit=gtk3' '--with-toolkit-scroll-bars'
 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector
 --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall'
 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro'
 'CPPFLAGS=-D_FORTIFY_SOURCE=2''

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  global-auto-complete-mode: t
  auto-complete-mode: t
  cua-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<help-echo> C-h v c o m m a n d l <backspace> - l i 
n e - a r g <tab> <return> ESC x r e p o r t - e m 
<tab> <return>

Recent messages:
Loading /var/cache/dictionaries-common/emacsen-ispell-default.el (source)...done
Loading debian-ispell...done
Loading /var/cache/dictionaries-common/emacsen-ispell-dicts.el (source)...done
Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)...done
Loading /etc/emacs/site-start.d/50python-docutils.el (source)...done
Loading /home/mcarifio/.emacs.d/lib/libemacs.el (source)...done
(lambda (a b) ...) quoted with ' rather than with #'
For information about GNU Emacs and the GNU system, type C-h C-a.
command-line-1: Unknown option `--user-emacs-directory'
Type C-x 1 to delete the help window.

Load-path shadows:
/usr/share/emacs/24.3/site-lisp/debian-startup hides /usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs/24.3/site-lisp/cmake-data/cmake-mode hides /usr/share/emacs/site-lisp/cmake-mode
/usr/share/emacs24/site-lisp/dictionaries-common/flyspell hides /usr/share/emacs/24.3/lisp/textmodes/flyspell
/usr/share/emacs/site-lisp/rst hides /usr/share/emacs/24.3/lisp/textmodes/rst
/usr/share/emacs24/site-lisp/dictionaries-common/ispell hides /usr/share/emacs/24.3/lisp/textmodes/ispell
/home/mcarifio/.emacs.d/elpa/flymake-0.4.13/flymake hides /usr/share/emacs/24.3/lisp/progmodes/flymake
/home/mcarifio/.emacs.d/elpa/sunrise-commander-20121024.2042/.dir-locals hides /usr/share/emacs/24.3/lisp/gnus/.dir-locals

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils help-mode easymenu auto-complete-config
go-autocomplete auto-complete edmacro kmacro popup
auto-complete-autoloads flymake-go-autoloads flymake-autoloads
flymake-jshint-autoloads gist-autoloads gh-autoloads eieio byte-opt
bytecomp byte-compile cconv go-mode-autoloads
graphviz-dot-mode-autoloads js-comint-autoloads js2-mode-autoloads
logito-autoloads multi-term-autoloads nginx-mode-autoloads
nose-autoloads pcache-autoloads finder-inf popup-autoloads
sunrise-commander-autoloads package uniquify advice help-fns
advice-preload cl-macs gv cl cl-lib cua-base devhelp time-date tooltip
ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd
fontset image regexp-opt fringe tabulated-list newcomment lisp-mode
register page menu-bar rfn-eshadow timer select scroll-bar mouse
jit-lock font-lock syntax facemenu font-core frame cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev
minibuffer loaddefs button faces cus-face macroexp files text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
dynamic-setting system-font-setting font-render-setting move-toolbar gtk
x-toolkit x multi-tty emacs)