enabled preprocesing for LRF input

src/calibre/ebooks/lrf/input.py

@@ -12,6 +12,7 @@
 from lxml import etree
 
 from calibre.customize.conversion import InputFormatPlugin
+from calibre.ebooks.conversion.utils import PreProcessor
 from calibre import guess_type
 
 class Canvas(etree.XSLTExtension):
@@ -419,4 +420,9 @@ def convert(self, stream, options, file_ext, log,
         styles.write()
         return os.path.abspath('content.opf')
 
+	def preprocess_html(self, html):
+        preprocessor = PreProcessor(log=getattr(self, 'log', None))
+        return preprocessor(html)
+
+