Added new tutorial on mouse picking and keyboard shortcuts

git-svn-id: http://www.openflipper.org/svnrepo/OpenFlipper/branches/Free@5423 383ad7c9-94d9-4d36-a494-682f7c89f535

Doxygen/PluginProgramming.docu

@@ -8,6 +8,7 @@
  * - \ref ex1
  * - \ref ex1b
  * - \ref ex2
+ * - \ref ex3
  *
  * \section plugin_sec Plugin Basics
  * 

Doxygen/concepts.docu

@@ -24,8 +24,9 @@
  * The user interactivity is gained by plain Qt mouse and keyboard events. If
  * the plugin wants to interact with the mouse or keyboard, it
  * has to implement the \ref MouseInterface and \ref KeyInterface
- * (for keyboard shortcuts, etc.). See \interfaces for an overview of
- * implementable interfaces.
+ * (for keyboard shortcuts, etc.). Read tutorial \ref ex3 to learn how
+ * to add mouse and keyboard interactivity to your plugin. Also see
+ * \interfaces for an overview of implementable interfaces.
  *
  * \section viewport_widget The viewport widget
  *

Doxygen/tutorial3.docu

+/*! \page ex3 Implementing mouse and keyboard interaction
+ *
+ * Coming soon...
+ */
\ No newline at end of file