Moving extern out of sub-namespace.
Moving extern out of sub-namespace.

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