initial union solution

CMakeLists.txt

include/intersections.h

include/point.h

include/print_triangle.h

include/triangle.h

src/debug_utilities/print_triangles.cpp

src/shapes/point.cpp

src/union.cpp

src/utilities/contourize.cpp

src/utilities/intersections.cpp

tests/union_tests.cpp

tests/unit_tests/contourize_tests.cpp

tests/unit_tests/edge_direction_intr_tests.cpp