create from_hdf5 in photon reactions to simplify photon export
create from_hdf5 in photon reactions to simplify photon export

amandalund/openmc,shikhar413/openmc,liangjg/openmc,walshjon/openmc,liangjg/openmc,smharper/openmc,shikhar413/openmc,mit-crpg/openmc,walshjon/openmc,paulromano/openmc,smharper/openmc,smharper/openmc,paulromano/openmc,mit-crpg/openmc,amandalund/openmc,walshjon/openmc,paulromano/openmc,liangjg/openmc,mit-crpg/openmc,amandalund/openmc,amandalund/openmc,mit-crpg/openmc,walshjon/openmc,smharper/openmc,shikhar413/openmc,liangjg/openmc,shikhar413/openmc,paulromano/openmc