minibar: adding a start category menu

+ The start category menu can be turned off by passing the option
  {startcat_menu:false} when starting the minibar.
+ Documentation updates.

src/www/minibar/about.html

@@ -167,11 +167,14 @@ Some implementation details:
    matching completions.
    (You can now use names of people when constructing sentences in the Letter
    grammar, for example.)
+ <li>[Added 2011-10-18] Added a button to display some grammar info and a
+   start category menu. The start category menu can be turned off by passing
+   the option <code>{startcat_menu:false}</code> when starting the minibar.
 </ul>
 
 <hr>
 <small class=modtime>
-<!-- hhmts start --> Last modified: Mon Aug 22 19:31:37 CEST 2011 <!-- hhmts end -->
+<!-- hhmts start --> Last modified: Tue Oct 18 17:18:42 CEST 2011 <!-- hhmts end -->
 </small>
 <address>
 <a href="http://www.cs.chalmers.se/~hallgren/">TH</a>