Draft: Add magma2 SPH scheme

I just added the MAGMA2 scheme in the branch MAGMA2 and are there some advices for the future implementation?

I added the two extra profiles:

• hydro_iact_cosmo.h and hydro_iact_sphenix.h. One is added the cosmological term and another is using the sphenix's diffusion parameter.
• There is a parameter called h_crit in the runner_iact_force and runner_iact_nonsym_force , which is the inverse of the resolution eta. And everytime I just change the parameter manually
• Also for the matrix inversion, I just paste the function invert_dimension_by_dimension_matrixin swift, and it might need clear a bit and call the function instead
• And I just directly use constant viscosity and diffusion parameters into the function without define it in the hydro_parameter.h. It also might need to change a bit
• Last thing is MAGMA2 use the quadratically mid point reconstruction and it is also worth to test the linearly reconstruction. Since it may increases the computing effciency.