Use the real constants module.

This is progressing refactor of the calibre code to make it more
readable, and transform it to something more coherent.

In this patch, there are changes regarding imports for some modules,
instead of polluting namespace of each module with some other modules
symbols, which often were imported from other modules. Yuck.

ebook_converter/ebooks/odt/input.py

@@ -1,11 +1,12 @@
 """
 Convert an ODT file into a Open Ebook
 """
-import os, logging
+import logging
+import os
 
-from lxml import etree
 from css_parser import CSSParser
 from css_parser.css import CSSRule
+from lxml import etree
 
 from odf.odf2xhtml import ODF2XHTML
 from odf.opendocument import load as odLoad
@@ -14,15 +15,9 @@ from odf.namespaces import TEXTNS as odTEXTNS
 
 from ebook_converter import CurrentDir, walk
 from ebook_converter.ebooks.oeb.base import _css_logger
-from ebook_converter.utils.xml_parse import safe_xml_fromstring
 from ebook_converter.polyglot.builtins import as_bytes
 
 
-__license__ = 'GPL v3'
-__copyright__ = '2008, Kovid Goyal kovid@kovidgoyal.net'
-__docformat__ = 'restructuredtext en'
-
-
 class Extract(ODF2XHTML):
 
     def extract_pictures(self, zf):
@@ -46,7 +41,7 @@ class Extract(ODF2XHTML):
                 ol.set('start', val)
 
     def fix_markup(self, html, log):
-        root = safe_xml_fromstring(html)
+        root = etree.fromstring(html)
         self.filter_css(root, log)
         self.extract_css(root, log)
         self.epubify_markup(root, log)