all main wml tools: use filter(), map() and zip() from Python 3

The main difference is that these functions return generators instead of lists. This actually breaks wmlscope's collision detection, which will be fixed in my next commit.

data/tools/wesnoth/wmliterator.py

@@ -21,6 +21,7 @@ Limitations:
 """
 
 from __future__ import print_function, unicode_literals
+from future_builtins import filter, map, zip
 
 from functools import total_ordering
 import sys, re, copy, codecs

data/tools/wesnoth/wmltools.py

@@ -4,6 +4,7 @@ wmltools.py -- Python routines for working with a Battle For Wesnoth WML tree
 """
 
 from __future__ import print_function, unicode_literals
+from future_builtins import filter, map, zip
 
 from functools import total_ordering
 import collections, codecs

data/tools/wmlindent

@@ -62,6 +62,7 @@ indent already zero; these two conditions strongly suggest unbalanced WML.
 """
 
 from __future__ import print_function, unicode_literals
+from future_builtins import filter, map, zip
 
 import sys, os, getopt, filecmp, re, codecs
 from wesnoth import wmltools

data/tools/wmllint

@@ -182,6 +182,7 @@
 #
 
 from __future__ import print_function, unicode_literals
+from future_builtins import filter, map, zip
 
 import sys, os, re, getopt, string, copy, difflib, time, gzip, codecs
 from wesnoth.wmltools import *

data/tools/wmlscope

@@ -94,6 +94,7 @@
 # sets the warning level.
 
 from __future__ import print_function, unicode_literals
+from future_builtins import filter, map, zip
 
 import sys, os, time, re, getopt, hashlib, glob, codecs
 from wesnoth.wmltools import *
@@ -448,7 +449,7 @@ Usage: wmlscope [options] dirpath
             collisions = []
             for (namespace, filename) in xref.filelist.generator():
                 with open(filename, "rb") as ifp: # this one may be an image or a sound, so don't assume UTF8 encoding
-                    collisions.append(hashlib.md5(ifp.read()).digest())
+                    collisions.append(hashlib.md5(ifp.read()).hexdigest()) # hexdigest can be easily printed, unlike digest
             collisions = zip(xref.filelist.flatten(), collisions)
             hashcounts = {}
             for (n, h) in collisions: