bugdown: Fix patterns ordering in Markdown extension.

- Put 'modal_link' and 'link' inline patterns after avatar inline pattern
  to correct applying them to parsed text.

Fixes:  zulip#1654

zerver/lib/bugdown/__init__.py

@@ -982,14 +982,14 @@ def extendMarkdown(self, md, md_globals):
         md.inlinePatterns.add(
             'modal_link',
             ModalLink(r'!modal_link\((?P<relative_url>[^)]*), (?P<text>[^)]*)\)'),
-            '>backtick')
+            '>avatar')
         md.inlinePatterns.add('usermention', UserMentionPattern(mention.find_mentions), '>backtick')
         md.inlinePatterns.add('emoji', Emoji(r'(?<!\w)(?P<syntax>:[^:\s]+:)(?!\w)'), '_end')
         md.inlinePatterns.add('unicodeemoji', UnicodeEmoji(
             u'(?<!\\w)(?P<syntax>[\U0001F300-\U0001F64F\U0001F680-\U0001F6FF\u2600-\u26FF\u2700-\u27BF])(?!\\w)'),
             '_end')
 
-        md.inlinePatterns.add('link', AtomicLinkPattern(markdown.inlinepatterns.LINK_RE, md), '>backtick')
+        md.inlinePatterns.add('link', AtomicLinkPattern(markdown.inlinepatterns.LINK_RE, md), '>avatar')
 
         for (pattern, format_string) in self.getConfig("realm_filters"):
             md.inlinePatterns.add('realm_filters/%s' % (pattern,),