added new rendering mode with particles.

* Change MPI_Reduce -> MPI_Allreduce so that if not all rank post it, renderer freezes
* Added new rendering mode with particles. The appropariate parms.txt files is in paramsNew.txt. To enter new rendering mode press 'p' after the renderer starts

*Know issues:  problems with parameters read from the params file if new volumetric rendering mode is default.
revert back to 'true'. This was used for debugging step, not good to have it in production.