ParaView Support: Further Conversions

[ax3l]

We will have to add some more tools to the xdmf converter:

• [x] #318 poly's and grid: do we need two xdmf files? (mailing list: yes)
• [ ] add correct scaling for dxdydz (opt-out)
• [ ] add and scale by units: cells, quantities, time step, ... (opt-in)
• [ ] adding the full box offsets due to moving window (opt-in)
• [x] #216 can we somehow move our arbitrary scalar user attribute values into xdmf, too? (e.g. mu0, eps0, ...)

This is a follow up to https://github.com/ComputationalRadiationPhysics/libSplash/pull/96#issuecomment-35485422

[f-schmitt]

see #216

[f-schmitt]

yes, we are going to need two xdmf files for poly and grid data

[f-schmitt]

[1] will be fixed with #318