Add new cGH entries cctk_level and cctk_block. These complement the existing cctk_patch and cctk_tile_{min,max} fields, and allow the compute kernels to know on which part of the grid structure they are operating. This is mostly interesting for producing better debugging output.

There are also new #defines CCTK_HAVE_CGH_LEVEL and CCTK_HAVE_CGH_BLOCK to indicate that these new fields are present.

See https://bitbucket.org/cactuscode/cactus/pull-requests/156 .

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2744/cactus-new-cgh-entries-cctk_level