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**
irony is more fun with proper english ;)
otherwise, I didn't get [it](http://dict.leo.org/#/search=relay&searchLoc=0&resultOrder=basic&multiwordShowSingle=on) ;)