Remove `output_format == 4` option (hdf and/or netcdf)?

[rjleveque]

When re-writing all the valout.f90 files for https://github.com/clawpack/amrclaw/pull/275, I noticed that output_format == 4 sometimes means hdf and other places means netcdf although I don't think either works. In particular we decided at some point thatnetcdf format is not appropriate for AMR data so we should not support that at all.

@mandli, does the hdf option work at all? Several places an valout.f90 files it stops with an error message if output_format == 4, so I suspect not.

Can I just remove all this code to clean up the files?

Same question for GeoClaw.

[mandli]

Not that I am aware of.