Merge Crusty82s changes for StereoSLAM

	modified:   cvt/util/Signal.h
	new file:   cvt/vision/features/GridFilter.cpp
	new file:   cvt/vision/features/GridFilter.h
	modified:   cvt/vision/slam/stereo/StereoSLAM.cpp
	modified:   cvt/vision/slam/stereo/StereoSLAM.h
Added iters to PointSet and GridFilter to Features

	modified:   cvt/geom/PointSet.h
	modified:   cvt/vision/features/FeatureSet.cpp
	modified:   cvt/vision/features/FeatureSet.h
MultiScale BRIEF and PMHuberStereo stuff

	modified:   cvt/CMakeLists.txt
	modified:   cvt/cl/kernel/pmhstereo.cl
	modified:   cvt/vision/ImagePyramid.h
	modified:   cvt/vision/IntegralImage.h
	modified:   cvt/vision/PMHuberStereo.cpp
	modified:   cvt/vision/PMHuberStereo.h
	modified:   cvt/vision/features/BRIEF.h
	modified:   cvt/vision/features/FeatureDescriptorExtractor.h