hydro restart into finer

[ajnonaka]

For hydro, Add a new 'init type' that reads in a plotfile or checkpoint and injects the data into a finer-by-X refinement ration and then does a projection

[ajnonaka]

Now implemented. Think of this as a new simulation from time step zero that just happens to initialize velocity from a plotfile with (possibly) coarser resolution.
set prob_type=-1 and set, .e.g,
plot_init_file = "plt0000003"
This works for any refinement ratio; and does error checking to make sure the refinement is clean and the same in each direction.
The code takes care of all parallel copy tricks for you, so for the new simulation define whatever max_grid_size you want/need .