Export dialog keeps last config. Updated "clear the cache" to remove all visible images/trajectory/background color.

git-svn-id: http://rtabmap.googlecode.com/svn/trunk/rtabmap@1811 f169173b-cf89-36c8-b27e-44dbe73f0c83

guilib/include/rtabmap/gui/CloudViewer.h

@@ -127,6 +127,7 @@ public:
 
 	void setTrajectoryShown(bool shown);
 	void setTrajectorySize(int value);
+	void clearTrajectory();
 
 	void removeAllClouds(); //including meshes
 	bool removeCloud(const std::string & id); //including mesh

guilib/include/rtabmap/gui/MainWindow.h

@@ -63,6 +63,7 @@ class PdfPlotCurve;
 class StatsToolBox;
 class DetailedProgressDialog;
 class TwistGridWidget;
+class ExportCloudsDialog;
 
 class RTABMAPGUI_EXP MainWindow : public QMainWindow, public UEventsHandler
 {
@@ -240,6 +241,7 @@ private:
 	//Dialogs
 	PreferencesDialog * _preferencesDialog;
 	AboutDialog * _aboutDialog;
+	ExportCloudsDialog * _exportDialog;
 
 	QSet<int> _lastIds;
 	int _lastId;