More useful hdf5 error messages

[Yurlungur]

Currently hdf5 does not tell you what group or file failed when it fails to open a handle. We need to figure out some kind of infrastructure to report that for spiner.

[adamdempsey90]

We recently ran into this with a mysterious HDF5 crash due to a bad matid group name in the spiner file. We can add some pre-checks checking that groups exist before pulling the trigger and doing the read.