Sanitize pane titles and window and session names more consistently and

strictly, prevents C0 characters and other nonvisible characters causing
problems. Reported (with a different fix) by Chris Monardo in GitHub
issue 4999.

tmux.c

@@ -34,6 +34,7 @@
 #include <time.h>
 #include <unistd.h>
 #include <util.h>
+#include <vis.h>
 
 #include "tmux.h"
 
@@ -285,6 +286,23 @@ get_timer(void)
 	return ((ts.tv_sec * 1000ULL) + (ts.tv_nsec / 1000000ULL));
 }
 
+char *
+clean_name(const char *name, const char* forbid)
+{
+	char	*copy, *cp, *new_name;
+
+	if (*name == '\0' || !utf8_isvalid(name))
+		return (NULL);
+	copy = xstrdup(name);
+	for (cp = copy; *cp != '\0'; cp++) {
+		if (strchr(forbid, *cp) != NULL)
+			*cp = '_';
+	}
+	utf8_stravis(&new_name, copy, VIS_OCTAL|VIS_CSTYLE|VIS_TAB|VIS_NL);
+	free(copy);
+	return (new_name);
+}
+
 const char *
 sig2name(int signo)
 {