Refactor to factory pattern for disparity and add sgbm back

cv-node/CMakeLists.txt

cv-node/include/ftl/algorithms/opencv_sgbm.hpp

cv-node/include/ftl/algorithms/rtcensus.hpp

cv-node/include/ftl/disparity.hpp

cv-node/include/ftl/rtcensus.hpp

cv-node/src/algorithms/fixstars_sgm.cpp

cv-node/src/algorithms/opencv_bm.cpp

cv-node/src/algorithms/opencv_sgbm.cpp

cv-node/src/algorithms/rtcensus.cpp

cv-node/src/disparity.cpp

cv-node/src/main.cpp