fix #139

* swank-presentations.lisp (lookup-and-save-presented-object-or-lose):
new slimefun, to take temporary presentations (e.g. from sldb or
slime-inspector) and turn them into permanent presentations in the
global presentation-id-object tables.

* slime-presentations.el (slime-copy-presentation-to-repl): rewrite,
including use of lookup-and-save-presented-object-or-lose, but also
restoring insertion of the presentation into the repl editing stream.