bugdown: Use our local copy of fenced_code

And wire it up to our local copy of codehilite.  This fixes highlighting in
fenced code blocks, e.g.

~~~~ .js
var x = function () {
    return "hi";
};
~~~~

(imported from commit 0efb0c9b98a3acdf55e18bb1918af7960f3425be)

zephyr/lib/bugdown/__init__.py

@@ -4,7 +4,7 @@ import traceback
 import re
 
 from zephyr.lib.avatar  import gravatar_hash
-from zephyr.lib.bugdown import codehilite
+from zephyr.lib.bugdown import codehilite, fenced_code
 
 class Gravatar(markdown.inlinepatterns.Pattern):
     def handleMatch(self, match):
@@ -76,10 +76,11 @@ def convert(md):
         _md_engine = markdown.Markdown(
             safe_mode     = 'escape',
             output_format = 'html',
-            extensions    = ['fenced_code', 'nl2br',
+            extensions    = ['nl2br',
                 codehilite.makeExtension(configs=[
                     ('force_linenos', False),
                     ('guess_lang',    False)]),
+                fenced_code.makeExtension(),
                 Bugdown()])
 
     try:

zephyr/lib/bugdown/fenced_code.py

@@ -77,7 +77,7 @@ Dependencies:
 
 import re
 import markdown
-from markdown.extensions.codehilite import CodeHilite, CodeHiliteExtension
+from zephyr.lib.bugdown.codehilite import CodeHilite, CodeHiliteExtension
 
 # Global vars
 FENCED_BLOCK_RE = re.compile( \
@@ -130,7 +130,7 @@ class FencedBlockPreprocessor(markdown.preprocessors.Preprocessor):
                 # is enabled, so we call it to highlite the code
                 if self.codehilite_conf:
                     highliter = CodeHilite(m.group('code'),
-                            linenos=self.codehilite_conf['force_linenos'][0],
+                            force_linenos=self.codehilite_conf['force_linenos'][0],
                             guess_lang=self.codehilite_conf['guess_lang'][0],
                             css_class=self.codehilite_conf['css_class'][0],
                             style=self.codehilite_conf['pygments_style'][0],