Overloadable and Registerable Functions in Comm

Function	Default
CCTK_SyncGroup
CCTK_SyncGroupsByDirI
CCTK_EnableGroupStorage
CCTK_DisableGroupStorage
CCTK_EnableGroupComm
CCTK_DisableGroupComm
CCTK_Barrier
CCTK_Reduce
CCTK_Interp
CCTK_ParallelInit