Cantera 3.0 adds "native" support for working with HDF5 files using libhdf5. Supporting this feature with the conda packages requires linking to a specific version of hdf5, and we need to decide how to handle this.

Some possibilities:

• Link against the latest packaged version of libhdf5 and leave it at that
• Provide packages linking to different versions of libhdf5, with the hdf5 version included in the version tag
• Provide packages with and without libhdf5 dependencies, with the version tag specified so that installing with HDF5 is preferred

I think the last option is probably the best way to avoid creating dependency problems that prevent users from installing specific Cantera versions without downgrading other packages (for example, when users who also want to have h5py installed install a version of that that link to a newer version of HDF5 than is compatible with a given Cantera release).