A fix for PointSampleBase

This is a proposed fix for the parallel logic in PointSamplerBase, this includes one major improvement.
- This object was calling the point locater on every supplied point on every process, this patch divides up the points so each process is responsible for some portion of this points.

However, this introduces some logic to divide up the point indices among the processes. I put some logic in initialize() to do this, but I am not sure if it is the best. If there is a better way to do this localization let me know.
This already means you're headed in the wrong direction.  I haven't looked at why you need this yet... but whatever it is it has to change...