more import cleanups

Cython/CodeWriter.py

-from Cython.Compiler.Visitor import TreeVisitor
-from Cython.Compiler.Nodes import *
-from Cython.Compiler.ExprNodes import *
-
 """
 Serializes a Cython code tree to Cython code. This is primarily useful for
 debugging and testing purposes.
@@ -10,6 +6,9 @@ The output is in a strict format, no whitespace or comments from the input
 is preserved (and it could not be as it is not present in the code tree).
 """
 
+from Cython.Compiler.Visitor import TreeVisitor
+from Cython.Compiler.ExprNodes import *
+
 class LinesResult(object):
     def __init__(self):
         self.lines = []

Cython/Plex/Regexps.py

@@ -6,7 +6,6 @@
 #
 #=======================================================================
 
-import array
 import types
 from sys import maxint as maxint
 

Cython/Plex/Transitions.py

@@ -5,7 +5,6 @@
 #   for speed.
 #
 
-from copy import copy
 from sys import maxint as maxint
 
 class TransitionMap(object):

Cython/TestUtils.py

 import Cython.Compiler.Errors as Errors
 from Cython.CodeWriter import CodeWriter
-from Cython.Compiler.ModuleNode import ModuleNode
-import Cython.Compiler.Main as Main
 from Cython.Compiler.TreeFragment import TreeFragment, strip_common_indent
 from Cython.Compiler.Visitor import TreeVisitor, VisitorTransform
 from Cython.Compiler import TreePath