ice-9 slib

[Kevin Ryde]

ice-9/slib tries to do the same as guile.init which comes with slib,
but hasn't kept up to date.  Each new slib is different, so it's
almost impossible to be correct anyway.

slib already comes with instructions for running under guile, I think
it'd be better to make that the main way to use slib, and remove
ice-9/slib.

Or maybe ice-9/slib could be kept for compatibility, doing the
equivalent of "guile -l guile.init", though I didn't have success
attempting that (I don't think I switched into the main guile-user
module for the load correctly).