Multi Species Particle Load from hdf5

- rewrite how partilces are loaded from HDF5 file
- add support for arbitrary species count
- particles load now done on gpu
- remove old method
- SimulationHelper: show init time in output

**Please do not merge before #514**
As you don't change `gridOffset` between here and its assignement, why not using `domInfo.localDomain.offset` directly which has the clear naming