When DAGMC fails during initialisation OpenMC should halt

[makeclean]

When initialising a DAGMC problem, there can be malformed geometries which do not conform to the requirements of DAGMC, e.g. a user may have forgotten to imprint, or surfaces could be missing, sometimes init_OBBTree() can fail, currently this failure is echoed to screen, but no further action is taken. We should likely catch the error and terminate. Right now we use the MOAB macro MB_CHK_ERR_CONT, maybe we either should raise an exception or maybe switch to a different macro such as MB_SET_GLB_ERR. Either way, right now OpenMC happily carries on.