Allow zero-size domains with invalid offsets

 - allows to read zero domains with from out-of-bounds offsets
   to ensure that all processes participate in collective requests
Allow zero-size domains with invalid offsets

 - allows to read zero domains with from out-of-bounds offsets
   to ensure that all processes participate in collective requests
Merge branch 'za-after-end' of github.com:ComputationalRadiationPhysics/libSplash into za-after-end
Merge pull request #92 from ComputationalRadiationPhysics/za-after-end

Zero domain access after end of data