ADDED: OSC 133 semantic prompt marks

Updates libedit and xpce.  The commandline editor marks its prompts and
the line it reads with the FinalTerm OSC 133 sequences, and the Epilog
terminal reads them: it now knows when there is a line being edited and
where it starts, rather than deducing it from bracketed paste.  That
gives click-to-move-the-caret back to vi mode, and terminals with shell
integration (iTerm2, kitty, WezTerm, VS Code) get prompt navigation over
a swipl session for free.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T13zyETRgTwZhjk383aj5n

Author: JanWielemaker

man/threads.plx

@@ -1456,6 +1456,11 @@ The Epilog terminal:
     location using OSC~8 terminal embedded URLs. Control-click opens
     the built-in editor (edit/1) or an editor of the user's choice.
     Clickable links are also supported for help/1 output.
+    \item Moves the caret to a click in the line being edited.  The
+    terminal knows which line that is because the commandline editor
+    marks its prompts using OSC~133 \jargon{semantic prompt} sequences;
+    a shell or other program started in the window that does the same
+    gets the same service.
     \item Uses, as does \program{swipl}, a modified version of libedit
     for commandline editing.  The same commandline editor is used on all
     platforms that support XPCE (Windows, macOS, Linux and other POSIX