Convert calibre modules to ebook_converter.

Here is the first batch of modules, which are needed for converting
several formats to LRF. Some of the logic has been change, more cleanups
will follow.

ebook_converter/ebooks/oeb/transforms/data_url.py

@@ -6,14 +6,14 @@ __license__ = 'GPL v3'
 __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import re
-from calibre.ebooks.oeb.base import XPath, urlunquote
-from polyglot.builtins import as_bytes
+from ebook_converter.ebooks.oeb.base import XPath, urlunquote
+from ebook_converter.polyglot.builtins import as_bytes
 
 
 class DataURL(object):
 
     def __call__(self, oeb, opts):
-        from calibre.utils.imghdr import what
+        from ebook_converter.utils.imghdr import what
         self.log = oeb.log
         attr_path = XPath('//h:img[@src]')
         for item in oeb.spine:
@@ -29,7 +29,7 @@ class DataURL(object):
                     continue
                 if ';base64' in header:
                     data = re.sub(r'\s+', '', data)
-                    from polyglot.binary import from_base64_bytes
+                    from ebook_converter.polyglot.binary import from_base64_bytes
                     try:
                         data = from_base64_bytes(data)
                     except Exception:
@@ -46,7 +46,7 @@ class DataURL(object):
 
     def convert_image_data_uri(self, data, fmt, oeb):
         self.log('Found image encoded as data URI converting it to normal image')
-        from calibre import guess_type
+        from ebook_converter import guess_type
         item_id, item_href = oeb.manifest.generate('data-url-image', 'data-url-image.' + fmt)
         oeb.manifest.add(item_id, item_href, guess_type(item_href)[0], data=data)
         return item_href