-initial work on a new function, mean_square_displacement_by_species(), to calculate MSD values from a trajectory using MDAnalysis [I am transplanting and modifying / generalizing the code from my previous work on influenza]
-working to improve the new mean_square_displacement_by_species() function:
-documentation now correctly indicates Return variable as dict_MSD_values_this_replicate
-I've now adjusted the name of the above variable to dict_MSD_values, and removed some extraneous code as a result of this simplification