Closes #139: restore presentation insertion into editing stream

* contrib/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.

* contrib/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.