Add command to print the enstrophy of the initial condition

src/constants.cpp

@@ -21,6 +21,7 @@ limitations under the License.
 #define COMMAND_QUIET 3
 #define COMMAND_RESUME 4
 #define COMMAND_LYAPUNOV 5
+#define COMMAND_ENSTROPHY_PRINT_INIT 6
 
 #define DRIVING_ZERO 1
 #define DRIVING_TEST 2