major fix of communication pattern

• The notification function 'sc_notify' of the used underlying library libsc does not guarantee receiving notifications of every sending process. Deadlocks happened in some rare cases with random distributed particles due to not knowing all senders. A simple change to the blocking notification function 'sc_notify_allgather' did help here.
• In the first round of generating the random distributed particles the particles where communicated to their belonging processes. But a second call to 'pchase_world_insert_particles' is needed to ensure that all particles are sorted into their belonging quadrants.
• 'pchase_world_insert_particles' needs to be split up in the next release

parallel particle chasing

This is v1.0 of particleChase. Everybody is free to fork and adapt this program for his needs. Due to the high scalability of p4est - the forest of octree structure - only little development is necessary to adapt this particle mover and add functionality like the fast multipole method (FMM) on top.

Feel free to contact me for further information or implementation issues.

Pre-parallel version

We gained huge speedup by inserting all moved particles in a row.