amr2cube is already used somewhere in RAMSES

remove unused pieces of code

still work in progress

add a mpi type for cell (in dev)
prepare displacements for cells
remove cells larger than cubes

process id is the id of the process that will write the cell in the end

not finished, partially tested

if level and position of 2 cells are equal, the 2 cells are identical

Modify other files accordingly
Correct some bugs
Has not bet tested !!!

Copy to a new cell
Is_sup returns true if level is >, then x >, then y>, then z>

Bug correction in cell_m related to removal of allocate_cells routine

New type for cells with everything needed for an amr/hydro cell