replace renders to render in every files

pymath/expression.py

@@ -2,7 +2,7 @@
 # encoding: utf-8
 
 from .generic import Stack, flatten_list, expand_list, isNumber, isOperator
-from .renders import txt, post2in_fix, tex
+from .render import txt, tex
 from .str2tokens import str2tokens
 
 __all__ = ['Expression']

pymath/random_expression.py

@@ -3,7 +3,7 @@
 
 from random import randint
 from .expression import Expression
-from .renders import tex, txt
+from .render import tex, txt
 import re
 
 from .arithmetic import gcd

test/test_expression.py

@@ -8,7 +8,7 @@ import unittest
 from pymath.expression import Expression
 from pymath.fraction import Fraction
 from pymath.generic import first_elem
-from pymath.renders import txt, tex
+from pymath.render import txt, tex
 
 
 class TestExpression(unittest.TestCase):