Use new uifc.list mode flag WIN_BLANKOPTS

uifc option lists are always NULL-terminated string lists (not static
arrays of char arrays, as is often used in other UIFC utils), so grow
the ability to have blank options (list items).

This was needed for fileman.js to accurately edit extended file
descriptions that contain blank lines.

src/sbbs3/js_uifc.c

@@ -903,7 +903,7 @@ js_uifc_list(JSContext *cx, uintN argc, jsval *arglist)
 		JS_SET_RVAL(cx, arglist, JSVAL_FALSE);
 	} else {
 		rc=JS_SUSPENDREQUEST(cx);
-		JS_SET_RVAL(cx, arglist, INT_TO_JSVAL(uifc->list(mode,left,top,width,(int*)dptr,(int*)bptr,title,opts)));
+		JS_SET_RVAL(cx, arglist, INT_TO_JSVAL(uifc->list(mode|WIN_BLANKOPTS,left,top,width,(int*)dptr,(int*)bptr,title,opts)));
 		JS_RESUMEREQUEST(cx, rc);
 	}
 	strListFree(&opts);