Removing unneeded from __future__ import statements.

Since we are on Python 3.6 and up, we don't need those anymore.

ebook_converter/ebooks/mobi/reader/ncx.py

@@ -1,17 +1,14 @@
-#!/usr/bin/env python2
-# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
-from __future__ import absolute_import, division, print_function, unicode_literals
-
-__license__   = 'GPL v3'
-__copyright__ = '2012, Kovid Goyal <kovid@kovidgoyal.net>'
-__docformat__ = 'restructuredtext en'
-
 from ebook_converter import replace_entities
 from ebook_converter.ebooks.metadata.toc import TOC
 from ebook_converter.ebooks.mobi.reader.headers import NULL_INDEX
 from ebook_converter.ebooks.mobi.reader.index import read_index
 from ebook_converter.polyglot.builtins import iteritems, getcwd
 
+
+__license__   = 'GPL v3'
+__copyright__ = '2012, Kovid Goyal <kovid@kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
 tag_fieldname_map = {
         1:  ['pos',0],
         2:  ['len',0],