Also revise faces and consider stickers that exited non-locally.

* sly.el (sly-after-compile-functions)
(sly-before-compile-functions): Removed.
(sly-compilation-finished-hook): Change interface and document.
(sly-compilation-finished-hook): Removed
`sly-create-compilation-log' and `sly-maybe-list-compiler-notes'
(sly-compile-file): Just call `sly-compilation-finished'.
(sly-compile-region-function): New indirection.
(sly-compile-region-as-string): New function, default value for
`sly-compile-region-function'.
(sly-compile-string): Don't take hook arg.
(sly-compilation-finished): Take optional `message' arg.
(sly-maybe-show-xrefs-for-notes, sly-maybe-show-compilation-log)
(sly-show-compilation-log): Conform to new
`sly-compileation-finished' protocol.
(sly-create-compilation-log): Removed.
(sly-maybe-show-compilation-log): Much simplified.
(sly--insert-compilation-log): Renamed from
`sly-insert-compilation-log'
(sly-xref-recompilation-cont): Call `sly-compilation-finished'
with second arg.

* contrib/sly-stickers.el (sly-stickers): Use new
`sly-compile-region-function'
(sly-stickers-compile-region-aware-of-stickers): Renamed and
redone from `sly-stickers-commit-stickers'.

* contrib/sly-stickers.el (sly-stickers-fetch): Handle zombie
stickers.

* contrib/sly-stickers.el (sly-stickers-exited-non-locally-face): New face.
(nil): New debug section to nullify face specs.
(sly-stickers--populate-sticker): Consider aborted stickers.
(sly-stickers--mark-empty-sticker, sly-stickers-fetch): Rename
internal var `last-values-desc'
(sly-stickers-placed-face, sly-stickers-armed-face)
(sly-stickers-recordings-face): Better face defaults perhaps.

* contrib/slynk-stickers.lisp (:slynk-stickers): Import
COMPILE-STRING-FROM-EMACS.
(compile-for-stickers): Try to compile with stickers first.

* contrib/slynk-stickers.lisp (kill-stickers): New slyfun.