Added a ViewerEventHandler which manages full screen, file write, and help

output to osgProducer.  Removed FullSreenEventHandler as it is now superseeded
by ViewerEventHandler.

src/osgProducer/ViewerEventHandler.cpp

@@ -0,0 +1,74 @@
+#include <osgProducer/ViewerEventHandler>
+#include <osgDB/WriteFile>
+
+using namespace osgProducer;
+
+ViewerEventHandler::ViewerEventHandler(osgProducer::OsgCameraGroup* cg):
+    _cg(cg),
+    _writeNodeFileName("savedmodel.osg")
+{
+}
+
+bool ViewerEventHandler::handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter&)
+{
+    if(!_cg) return false;
+
+    if(ea.getEventType()==osgGA::GUIEventAdapter::KEYDOWN)
+    {
+
+        switch( ea.getKey() )
+        {
+          case 'f' :
+          {
+            Producer::CameraConfig* cfg = _cg->getCameraConfig();
+            for( unsigned int i = 0; i < cfg->getNumberOfCameras(); ++i )
+            {
+                Producer::Camera *cam = cfg->getCamera(i);
+                Producer::RenderSurface* rs = cam->getRenderSurface();
+                rs->fullScreen(!rs->isFullScreen());
+            }
+
+            return true;
+          }
+          case 'o' :
+          {
+            osg::Node* node = _cg->getSceneData();
+            if (node)
+            {
+                std::cout<<"writing file "<<_writeNodeFileName<<std::endl;
+                osgDB::writeNodeFile(*node,_writeNodeFileName.c_str());
+            }
+            
+            return true;
+          }
+
+          case osgGA::GUIEventAdapter::KEY_Help :
+          case '/' :
+          case '?' :
+          {
+            if (_cg->getApplicationUsage())
+            {
+                _cg->getApplicationUsage()->write(std::cout,_cg->getApplicationUsage()->getKeyboardMouseBindings());
+            }
+            
+            return true;
+          }
+
+        default:
+            break;
+
+        }
+    }
+    return false;
+
+}
+
+void ViewerEventHandler::accept(osgGA::GUIEventHandlerVisitor& gehv)
+{
+    gehv.visit(*this);
+}
+
+void ViewerEventHandler::getUsage(osg::ApplicationUsage& usage) const
+{
+    usage.addKeyboardMouseBinding("f","Toggle fullscreen");
+}