Bugs in particle output

[haykh]

• If species don’t have particles initially, they cannot be included into the particle output (get buffer error)
• When I did not specify any species, there was no particle output triggered at all (while default input says that in that case it should have all the species for output)
• with particles & MPI it just gets stuck in the first output

[haykh]

@jmahlmann if all good -- this should be merged. waiting for your green light