Change usages of xrange() to range()

In Python3, range() creates a generator rather than a list.

None of the parameters in the ranges changed looked large enough
to create an impact in memory in Python2.  Note: the only use of
range() was for iteration and did not need to be changed.

This is part of a series of changes to introduce Python3 support.

Change-Id: I50b665f9296ea160a5076c71f36a65f76e47029f

main.py

@@ -87,7 +87,7 @@ class _Repo(object):
     name = None
     glob = []
 
-    for i in xrange(0, len(argv)):
+    for i in range(len(argv)):
       if not argv[i].startswith('-'):
         name = argv[i]
         if i > 0: