Allows Typogrify to ignore user specified tags. Refs #1407

Typogrify interferes with certain sections of the output that it should not touch (see #1407 for more details).
This feature adds a setting called TYPOGRIFY_IGNORE_LIST which is a list of tag for Typogrify to ignore.

The following was updated:

 1. readers.py - if TYPOGRIFY_IGNORE_TAGS is present, then use it
 2. settings.ps - default TYPOGRIFY_IGNORE_TAGS to []
 3. contents/article_with_code_block.rst - an article with a code block for typogrify to ignore
 4. updated tests
 5. updated documentation

pelican/readers.py

@@ -456,11 +456,20 @@ class Readers(FileStampDataCacher):
         # eventually filter the content with typogrify if asked so
         if self.settings['TYPOGRIFY']:
             from typogrify.filters import typogrify
+
+            def typogrify_wrapper(text):
+                """Ensures ignore_tags feature is backward compatible"""
+                try:
+                    return typogrify(text, self.settings['TYPOGRIFY_IGNORE_TAGS'])
+                except TypeError:
+                    return typogrify(text)
+
             if content:
-                content = typogrify(content)
-                metadata['title'] = typogrify(metadata['title'])
+                content = typogrify_wrapper(content)
+                metadata['title'] = typogrify_wrapper(metadata['title'])
+
             if 'summary' in metadata:
-                metadata['summary'] = typogrify(metadata['summary'])
+                metadata['summary'] = typogrify_wrapper(metadata['summary'])
 
         if context_signal:
             logger.debug('signal {}.send({}, <metadata>)'.format(