Fix infinite loop in memfind()

- memfind used to loop forever trying to match shell_handlers
- match python2.8 and python3 in shbang line
- bump version to 5.3.1d
- this fixes #1 reported by cmsigler, thank you

lang/python.c

@@ -308,7 +308,8 @@ static void python_colorize_line(QEColorizeContext *cp,
 static ModeDef python_mode = {
     .name = "Python",
     .extensions = "py|pyt",
-    .shell_handlers = "python|python2.6|python2.7",
+    // XXX: should accept wildcards "python*"
+    .shell_handlers = "python|python2.6|python2.7|python2.8|python3",
     .keywords = python_keywords,
     .colorize_func = python_colorize_line,
     .colorize_flags = PYTHON_PYTHON,