Fills in a rectangular patch of valbig and aux, which contain solution and aux values on an input region. Values are needed at time time, and at level level.
In indices relative to valbig and aux, the lower-left corner of the patch is at (nrowst,ncolst). In global indices, its lower-left corner is at (ilo,jlo), and its upper-right corner is at (ihi,jhi).
First, the patch is filled with values obtainable from the level level grids. If any values are left unfilled, the remaining rectangle of unfilled values is enlarged by 1 (for later linear interpolation), and remaining values are recursively obtained from coarser levels.