add hooks to allow loading custom help documentation

EVENTS.txt

@@ -227,3 +227,11 @@ StartNewQueueManager: before trying to start a new queue manager; good for plugi
 RedirectToLogin: event when we force a redirect to login (like when going to a settings page on a remembered login)
 - $action: action object being shown
 - $user: current user
+
+StartLoadDoc: before loading a help doc (hook this to show your own documentation)
+- $title: title of the document
+- $output: HTML output to show
+
+EndLoadDoc: after loading a help doc (hook this to modify other documentation)
+- $title: title of the document
+- $output: HTML output to show

actions/doc.php

@@ -58,12 +58,24 @@ class DocAction extends Action
     function handle($args)
     {
         parent::handle($args);
+
         $this->title  = $this->trimmed('title');
+        $this->output = null;
+
+        if (Event::handle('StartLoadDoc', &$this->title, &$this->output)) {
+
             $this->filename = INSTALLDIR.'/doc-src/'.$this->title;
             if (!file_exists($this->filename)) {
                 $this->clientError(_('No such document.'));
                 return;
             }
+
+            $c = file_get_contents($this->filename);
+            $this->output = common_markup_to_html($c);
+
+            Event::handle('EndLoadDoc', $this->title, &$this->output);
+        }
+
         $this->showPage();
     }
 
@@ -93,9 +105,7 @@ class DocAction extends Action
      */
     function showContent()
     {
-        $c      = file_get_contents($this->filename);
+        $this->raw($this->output);
-        $output = common_markup_to_html($c);
-        $this->raw($output);
     }
 
     /**