Added key-indicator debugging info to StereoSLAM

Added StereoSLAMFootPrint, a class that collects data about things like
found feature count, filtered feature count, inlier percentages etc.
This is saved into a file and should provide useful insights about what
might be wrong with StereoSLAM and about how certain parameter changes
impact these key-indicators.

	modified:   cvt/CMakeLists.txt
	modified:   cvt/vision/features/RowLookupTable.cpp
	modified:   cvt/vision/slam/stereo/StereoSLAM.cpp
	modified:   cvt/vision/slam/stereo/StereoSLAM.h
	new file:   cvt/vision/slam/stereo/StereoSLAMFootPrint.cpp
	new file:   cvt/vision/slam/stereo/StereoSLAMFootPrint.h