Restructured the code. Every type is now in a separate file and has its own...

Restructured the code. Every type is now in a separate file and has its own headers which is easier to work through. Moved some functions to classes where it made more sense. Removing necessity for gradient_handle.h. Added cmake support. Create a folder build, cd to it and use 'cmake .. -DNETCDF_INCLUDE_DIR=/mnt/localscratch/include/ -DCODIPACK_INCLUDEDIR=/mnt/localscratch/include/ && make' to compile the code.