Lost particle plotting01

This pull request will give OpenMC the capability to plot particle tracks.  Through the commandline or the settings.xml file, OpenMC can be directed to output binary files that show the track a particle takes through the geometry.  The new utility "track.py" can then convert these files into a VTK poly data format which can then be viewed in Paraview.  This is intended as a debugging tool to help with geometry problems.

Note that VTK poly data allows attributes to be assigned to its points so it might be easy to modify the code so that the particle's energy, etc. is also plotted.