Moving to GitHub and cl-lib

[Helmut Eller]

As you may have heard, we're moving the SLIME repository to GitHub. The new
location is: https://github.com/slime/slime

The bug tracker will also be moved from Lunchpad to GitHub.

João Távora has already done some work in the new repository. In
particular SLIME now requires the cl-lib library.  As you probably know,
the Emacs maintaners have declared the cl library obsolete, and
encourage everybody to use the new names.  What used to be "find" from
the cl library is now called "cl-find" and in the cl-lib library.

If you're using Emacs 23 then you need to install cl-lib manually, i.e.
grab the .el file from http://elpa.gnu.org/packages/cl-lib.html and drop
it somewhere into Emacs' load-path.  Is that too much hassle?  Should we
include scripts to automate this or perhaps include cl-lib-3.0.el in our
repo?

cl-lib may or may not work with XEmacs. This poses the questions: are
there many XEmacs users left?  Would you be very unhappy if we drop
XEmacs support?  Or are you a "I'd be happier with XEmacs but GNU Emacs
is also OK" kind of person?

Helmut