Refactoring: removed some code duplication about transformation estimation and features (2D-3D) extraction.

Added Feature2D::generateKeypoints3D() for convenience.
Added parameter "Vis/PnPOpenCV2".
Added parameter "Vis/ForwardEstOnly".
Removed OdometryOpticalFlow class, replaced by OdometryF2F (frame-to-frame). To get the same previous OpticalFLow approach, parameter "Vis/CorType" should be set to 1.
Some parameters under group "OdomFlow/..." are now under "Vis/CorFlow...".
In Registration class, add computeTransformationMod() method to modify input signatures.
Added constructor Signature(SensorData) for convenience.
Modified words multimap used with cv::Point3f instead of pcl::PointXYZ to limit the use of PCL headers where they are not really required.
Added Stereo::create() for convenience.
Transform: fixed quaternion constructor where data_ was not initialized. Added parentheses operator for convenience.
DatabaseViewer: loading .rtabmap/rtabmap.ini instead of .rtabmap/dbViewer.ini when used from rtabmap application. Added vertical layout option for convenience.
MainWindow: fixed wrong Odometry speed values
ParametersToolBox: using QStackedWidget instead of a QToolBox for space, added "Restore Defaults" button.

corelib/include/rtabmap/core/EpipolarGeometry.h

@@ -86,6 +86,16 @@ public:
 
 	static cv::Mat findFFromCalibratedStereoCameras(double fx, double fy, double cx, double cy, double Tx, double Ty);
 
+
+	/**
+	 * if a=[1 2 3 4 6], b=[1 2 4 5 6], results= [(1,1) (2,2) (4,4) (6,6)]
+	 * realPairsCount = 4
+	 */
+	static int findPairs(
+			const std::map<int, cv::KeyPoint> & wordsA,
+			const std::map<int, cv::KeyPoint> & wordsB,
+			std::list<std::pair<int, std::pair<cv::KeyPoint, cv::KeyPoint> > > & pairs);
+
 	/**
 	 * if a=[1 2 3 4 6 6], b=[1 1 2 4 5 6 6], results= [(1,1a) (2,2) (4,4) (6a,6a) (6b,6b)]
 	 * realPairsCount = 5