Reduce duplication of 1d base state -> 3d MultiFab calculations

[harpolea]

Routines offloaded to the GPU now take the 1d base state mapped to a 3d MultiFab. This mapping is often done within the C++ wrapper function of these routines, which is likely to lead to lots of duplication, the same quantities being mapped repeatedly by different functions. It might be more efficient to do the mapping once (e.g. just after the base state is changed) and carrying this around rather than computing it on the fly every time it's needed.

[ajnonaka]

One tricky part is that some of the X_cart temporary multifabs are filled with things like "rho0", where rho0 is passed in to a function and could be rho0_old, rho0_new, or some temporarily created rho_nph.

[harpolea]

That's true. I wasn't thinking that this should be done for all of the X_carts, but I certainly noticed that there are an awful lot of w0_carts created, which seems rather inefficient

[ajnonaka]

agreed about w0_cart. makes the code much cleaner too, less to pass around if w0_cart is part of the MAESTRO class.

[ajnonaka]

I finished the first part of cleaning up w0_cart. w0_cart is now part of the MAESTRO class. the next step is to eliminate the calls that fill in w0_cart from w0. I think the idea is to fill in w0_cart from w0 immediately after make_w0 is called, and only then.

[ajnonaka]

ok done with eliminating unnecessary calls to fill w0_cart from w0. Still other base state arrays to consider.