Adding support for User Tags.

User Tags can present these format and they're insensitive:
- /ROLE_ADMIN
- /admin
- /a
- /u/#ID
- /ROLE_USER/@USERNAME
- /ROLE_MOD/@USERNAME (they virtually do the same thing, could present changes in notification importance)

ParsedownHAYFlavored.php

@@ -9,11 +9,13 @@ function __construct()
         $this->InlineTypes['-'][]= 'Radio';
         $this->InlineTypes['['][]= 'Survey';
         $this->InlineTypes['$'][] = 'InlineLaTeX';
+        $this->InlineTypes['/'][] = 'UserTag';
         $this->BlockTypes['$'][] = 'LaTeX';
         $this->BlockTypes['['][] = 'LaTeX';
         $this->inlineMarkerList .= '-';
         $this->inlineMarkerList .= '[';
         $this->inlineMarkerList .= '$';
+        $this->inlineMarkerList .= '/';
     }
 
     protected function blockList($Line, ?array $CurrentBlock = NULL)
@@ -116,6 +118,23 @@ protected function inlineInlineLaTeX($excerpt)
         }
     }
 
+    protected function inlineUserTag($excerpt)
+    {
+        if (preg_match('/^\/[\w#@]+(?:[\w#@\/-]+)?/i', $excerpt['text'], $matches))
+        {
+            return array(
+                'extent' => strlen($matches[0]),
+                'element' => array(
+                    'name' => 'span',
+                    'text' => $matches[0],
+                    'attributes' => array(
+                        'class' => 'usertag_unprocessed'
+                    )
+                )
+            );
+        }
+    }
+
     protected function blockLaTeX($line, $block)
     {
         if (preg_match('/^(\$\$\$|\[LaTeX\])/i', $line['text'], $matches))