tests: replace "from util import *" by explicit imports

tests/test_markup.py

@@ -11,8 +11,6 @@
 
 import re
 
-from util import *
-
 from docutils import frontend, utils, nodes
 from docutils.parsers import rst
 
@@ -21,6 +19,11 @@ from sphinx.util.pycompat import b
 from sphinx.writers.html import HTMLWriter, SmartyPantsHTMLTranslator
 from sphinx.writers.latex import LaTeXWriter, LaTeXTranslator
 
+from util import TestApp
+
+
+app = settings = parser = None
+
 def setup_module():
     global app, settings, parser
     texescape.init()  # otherwise done by the latex builder