* sly-trace-dialog.el (sly-trace-dialog-mode): Activate `sly-mode' minor mode.
Cleanup `sly-button-define-part-action' and its callers

* sly-buttons.el (sly-part-button-keymap): Keymap declaration is simpler.
(sly-button--popup-option-name)
(sly-button--popup-part-menu-options): Removed. Clever but horrible.
(sly-button-popup-part-menu-keymap): New keymap.
(sly-button-popup-part-menu): Use the rest of
`sly-button-popup-part-menu-keymap'.
(sly-button-define-part-action): Rewritten.
(sly-button-not-implemented): Removed.

* sly.el (sly-inspector-part): Use new action prop names.

* contrib/sly-mrepl.el (sly-mrepl): Use better
`sly-button-define-part-action'
(sly-mrepl-part): Use new action prop names.

* contrib/sly-trace-dialog.el (sly-trace-dialog-part): Use new action prop names.
Finish inspector converion to sly-button.el

* sly.el (sly-inspector-operate-on-point)
(sly-inspector-property-at-point, sly-inspector-operate-on-click):
Removed this silly function.
(sly-curry, sly-rcurry): Make properly lexical.
(sly-inspector-insert-more-button, sly-inspector-insert-ispec):
Use `sly-make-action-button'.
(sly-inspector-fetch-more): Use Emacs' button API