Modified the cosmological test case to make it fully compatible with GADGET-2...

Modified the cosmological test case to make it fully compatible with GADGET-2 in non-cosmo mode (!). Also removed all the unnecessary arrays.
This test case can be read by both GADGET-2 and swift as is.




Former-commit-id: db7c6f496f57773817475b7d62942d1498caa0e8