Added ssoutdir as a variable for defining the nest output directory

src/write_global_output.f90

@@ -79,7 +79,7 @@ call mpi_comm_rank (mpi_comm_world,iproc,ierr)
 
 if (iproc.eq.0) then
    if (params%nest) then
-     outdir='SSOUT'
+     outdir=nest%ssoutdir
    else
      outdir='OUT'
    endif