Splitting and moving generic.el.

[Lute Kamstra]

generic.el currently contains two facilities:

1. Defining major modes by means of define-generic-mode.

2. The definition of default-generic-mode and some setup code to use
   it automatically for some files.

I think 2. is a strange side-effect when you are using generic.el to
do 1.  So I propose to move 2. to generic-x.el, where it is more
appropriate.

And what about moving generic.el from lisp/ to lisp/emacs-lisp/?  That
seems the appropriate location.

Lute.