Merge branch '19-libelas' into 'master'

CMakeLists.txt

include/libelas/elas.h

include/libelas/elasDescriptor.h

include/libelas/elasFilter.h

include/libelas/elasImage.h

include/libelas/elasMatrix.h

include/libelas/elasTimer.h

include/libelas/elasTriangle.h

src/libelas/elas.cpp

src/libelas/elasDescriptor.cpp

src/libelas/elasFilter.cpp

src/libelas/elasMain.cpp

src/libelas/elasMatrix.cpp

src/libelas/elasTriangle.cpp

src/stereoContext.cpp

src/stereoWidget.cpp