Close #371: fix and detail documentation of sly-who-calls, etc

* sly.el (sly-who-calls): Mention `sly-list-callers' in the docstring.
(sly-calls-who): Mention `sly-list-callees' in the docstring.
(sly-list-callers): Mention `sly-who-calls' in the docstring.
(sly-list-callees): Mention `sly-calls-who' in the docstring.

* slynk/slynk-backend.lisp (calls-who): Fix docstring.

Release SLY 1.0.42

See NEWS.md for details.

* READNE.md: Update description.

* NEWS.md: release SLY 1.0.42.

* sly.el (Version): Bump to 1.0.42.  Update description.

* doc/sly.texi (SLYVER): 1.0.42.

abcl: fix inspector for a STRUCTURE-OBJECT with no inspectable parts

Unfortunately, not all system defined STRUCTURE-OBJECT instances
implement the getParts() protocol to expose their inspectable parts.
If this is the case, we now emit a message rather than bombing into an
error.

* slynk/backend/abcl.lisp: Rework it.

Cherry-picked-from: SLIME commit a4de28b
Co-authored-by: João Távora <joaotavora@gmail.com>

arglist-dispatch: better handling of closer-mop wrappers.

Display the arglist for the corresponding CL or SLYNK-MOP symbol.

* contrib/slynk-arglists.lisp (arglist-dispatch): Rework.

Co-authored-by: João Távora <joaotavora@gmail.com>
Cherry-pick-from: SLIME commit 5139e51

2.26.1

2.26

Release 2.25

2.24

2.23

Merge branch 'slime-catchup-2.22'