Refactor to C++

CMakeLists.txt

apps/CMakeLists.txt

apps/app.cpp

apps/scheme.c

include/field.h

include/group.h

include/ipre.h

include/matrix.h

include/vector.h

src/CMakeLists.txt

src/field.cpp

src/group.cpp

src/matrix.cpp

src/vector.cpp

tests/CMakeLists.txt

tests/test_field.cpp

tests/test_group.cpp

tests/test_matrix.cpp

tests/test_vector.cpp