Integrate filtering options between locate_and_measure and link_particles

[pennekampster]

Tracking is the most time-consuming aspect of BEMOVI so far. To cut time down for tracking, pre-filtering on the raw coordinates may be helpful: for instance, morphologies far outside the range encountered could be filtered out (this already happens due to size limits in the locate_and_measure, but more morphology variables could be included).

This requires that the link_particles function is changed to work on the particle.RData instead of the raw text files output by locate_and_measure.

[pennekampster]

The multicore version already uses the particle data as input, so could be easily adapted.