Maxwell working again on CPU.

CMakeLists.txt

include/connectivity.h

include/entity.h

include/entity_data.h

include/gmsh_io.h

include/gpu_support.hpp

include/maxwell_interface.h

include/silo_output.hpp

src/entity.cpp

src/entity_data.cpp

src/gmsh_io.cpp

src/maxwell_cpu.cpp

src/maxwell_gpu.cpp

src/maxwell_interface.cpp

src/maxwell_kernels_cuda.cu

src/maxwell_solver.cpp

src/silo_io.cpp

tests/profile_differentiation_gpu.cpp

tests/test_basics.cpp

tests/test_differentiation.cpp