add hdf5 dumpreader for PIConGPU

[skuschel]

• add dumpreader
• fix Every Field dumped should be allowed to have its own grid #30
• update dumpreader to new multi grid support interface: add mutiple grid support #38
• add simulationreader
• calculate grid offset correctly in case of moving window. See Dumped data axis order ComputationalRadiationPhysics/picongpu#924

cc @stetie @ax3l

[skuschel]

There is draft of its implementations here: https://github.com/skuschel/postpic/tree/picongpureader
@ax3l Do you know when PIConGPU produces OpenPMD conform output, so this becomes entirely obsolete?

[ax3l]

@skuschel I have a branch open that already implements the base standard and right now gets the particlePatches. It still lacks the ED-PIC extension: https://github.com/ax3l/picongpu/tree/topic-openPMD

The plan is to ship openPMD starting with the next release (freeze in a few weeks, release in ~1-2 month), need to see if this will include ED-PIC already: PIConGPU 0.2.0

[ax3l]

you will probably still need the simulationreader since that information is not stored in openPMD 1.X

[skuschel]

There will be a simulationreader (=time series reader) for OpenPMD anyways. Ok seems good, so its probably worth to just wait until picongpu uses OpenPMD. I will still leave the issue open, till this is done.