Issue 3354 - Enable extras module for Markdown inside HTML blocks

cms/converters.py

 # coding: utf-8
 
 # This file is part of the Adblock Plus web scripts,
 # Copyright (C) 2006-2015 Eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
@@ skipping 292 matching lines @@
         return match.group(0)
       else:
         return char
 
     escapes = {}
     for char in markdown.Markdown.ESCAPED_CHARS:
       escapes[char] = "&#" + str(ord(char)) + ";"
     for key, value in html_escapes.iteritems():
       escapes[key] = value
 
-    md = markdown.Markdown(output="html5", extensions=["attr_list"])
+    md = markdown.Markdown(output="html5",
+                           extensions=["attr_list", "markdown.extensions.extra"])

[saroyanm, 2015/11/26 13:49:50]

According to documentation extra extension include attr_list extension.
https://pythonhosted.org/Markdown/extensions/extra.html 
Also make sense to update README.md, replacing "Attribute Lists" reference to
the "extra" extension.

[kzar, 2015/11/26 14:01:34]

I read the documentation differently, but I gave it a try and it turns out
you're right. Done.

[Sebastian Noack, 2015/11/26 14:23:51]

Well, this is weird, but seems to be right. While there is a separate extension
for other features included with the "extra" extension. HTML block support is
only available if you enable the whole "extra" extension collection.

[saroyanm, 2015/11/26 14:29:48]

Yes I also had a doubt initially, they formulated it not clear, but it's
imitation of the PHP Extra ( https://michelf.ca/projects/php-markdown/extra/ ),
which do include the attribute list implementation, also I've checked the link
below according to which looks my doubts went away:
https://pythonhosted.org/Markdown/extensions/index.html#officially-supported-...

     md.preprocessors["html_block"].markdown_in_raw = True
 
     def to_html(s):
       return re.sub(r'</?p>', '', md.convert(s))
 
     result = self.insert_localized_strings(source, escapes, to_html)
     result = md.convert(result)
     result = re.sub(r"&#(\d+);", remove_unnecessary_entities, result)
     result = self.process_links(result)
     return result
@@ skipping 113 matching lines @@
         stack.pop()
       stack[-1]["subitems"].append(item)
       stack.append(item)
     return structured
 
 converters = {
   "html": RawConverter,
   "md": MarkdownConverter,
   "tmpl": TemplateConverter,
 }