Added license and license headers.

include/test.h

include/timecounter.h

src/CMakeLists.txt

src/libgmshdg/CMakeLists.txt

src/libgmshdg/connectivity.cpp

src/libgmshdg/entity.cpp

src/libgmshdg/entity_data.cpp

src/libgmshdg/gmsh_io.cpp

src/libgmshdg/kernels_cpu.cpp

src/libgmshdg/kernels_cuda.cu

src/libgmshdg/kernels_gpu_mi.cpp

src/libgmshdg/param_loader.cpp

src/libgmshdg/physical_element.cpp

src/libgmshdg/reference_element.cpp

src/libgmshdg/silo_io.cpp

src/maxwell/CMakeLists.txt

src/maxwell/maxwell_common.cpp

src/maxwell/maxwell_cpu.cpp

src/maxwell/maxwell_gpu.cpp

src/maxwell/maxwell_interface.cpp