vis: remove trailing new line before executing prompt command

This should actually make the search history functionality work.

The :-commands already worked because of commit e745b5e.
Removing all trailing white spaces would be the wrong thing
to do for the search, because they might be part of the
desired search string.

vis-prompt.c

@@ -70,14 +70,18 @@ static const char *prompt_enter(Vis *vis, const char *keys, const Arg *arg) {
 		return keys;
 	}
 
+	size_t len = strlen(cmd);
+	if (len > 0 && cmd[len-1] == '\n')
+		cmd[len-1] = '\0';
+
 	bool lastline = (range.end == text_size(txt));
 
 	prompt_restore(prompt);
 	if (vis_prompt_cmd(vis, cmd)) {
 		prompt_hide(prompt);
 		if (!lastline) {
 			text_delete(txt, range.start, text_range_size(&range));
-			text_insert(txt, text_size(txt), cmd, strlen(cmd));
+			text_appendf(txt, "%s\n", cmd);
 		}
 	} else {
 		vis->win = prompt;