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**~~
Actually, double brackets are *bad* and clang would even complain about it: https://github.com/ax3l/pngwriter/pull/32