add tensor

Author: Jullija

src/core/CMakeLists.txt

@@ -101,7 +101,7 @@ if(NOT MP_UNITS_API_FREESTANDING)
                include/mp-units/ext/format.h
                include/mp-units/cartesian_vector.h
                include/mp-units/cartesian_tensor.h
-               include/mp-units/format.h
+               include/mp-units/format.h # deprecated
                include/mp-units/math.h
                include/mp-units/ostream.h
                include/mp-units/random.h