Large reorg of FUEL codebase

* Modernize the FUEL elisp code for Emacs 24.3. Emacs 24.3 deprecated
the old 'cl lib and standardized a new 'cl-lib lib to put the name
clash issues to rest once and for all. This version of FUEL now requires
24.3.
* Move FUEL code that was needed by factor-mode into factor-mode and
rename appropriately. factor-mode and FUEL are now clearly separated
and FUEL depends on factor-mode.
* Set up FUEL with appropriate autoloads so that it's Emacs 24 package
manager friendly. FUEL can now be uploaded to MELPA or some similar
package manager.
* Changed the Factor faces for font locking to inherit from the default
Emacs faces rather than defaulting to other colors. This means that
Emacs themes will work for Factor code out of the box. Further
tailoring of Factor-specific faces can be done by users themselves.
* Cleaned up a lot of code to use Emacs conventions
(define-defined-mode, define-minor-mode, indent-function, etc) and added
a propery syntax table so that paren matching works, and word/symbol
skipping works.
* Added a new minor mode, fuel-autohelp-mode, that displays the help for
the symbol under point in another window. A fusion of fuel-autodoc-mode
and fuel-help-mode that's quite handy for reading Factor code.
FUEL: Fix Emacs package metadata for MELPA recipe
sequences.extras: adding remove-last.