* sly.el (sly-inspector-mode-map, sldb-mode-map)
(sly-xref-mode-map): Use `set-keymap-parent' and set
`button-buffer-map' as the parent.

* contrib/sly-trace-dialog.el (sly-trace-dialog-mode-map): Use
`set-keymap-parent' and set `button-buffer-map' as the parent.
(sly-trace-dialog-part, sly-trace-dialog-spec): Don't skip these buttons.
(sly-trace-dialog--insert-trace): Skip just the "id string" button
* contrib/swank-trace-dialog.lisp: Reorganized functions.
(trace-part-or-lose, trace-or-lose): Renamed and reworked from
FIND-TRACE-PART-OR-LOSE and FIND-TRACE