Update plot_3d_fr.py

[tm132]

Updates to plot_3d_fr.py (quality of life updates):

• fix bug that prevents it from working removed this, as there are bigger issues here that need to be looked at,
• add a few new options
  • -i for interactive mode (this needs to be runnable without the gui so that it can be used as part of an automated process)
  • -o <output directory> (allow the dir where the output plots are written to to be specified)
  • Change the default output dir to the location where frames.bin is found