Tracing particles with script. Plot resulting positions.
  - Tracing Init is now a program instead of a script.
  - Created a script for generating initialization files.
  - Read particle positions and velcoities into an array, not a structure.
  - Trace reader returns an array.
  - Diff3D keyword has propagated to MrSim_Whcih and MrSim2D.
  - GetYCell handles 1-element dimensions (y in 2D).
  - Centralized fMap dir