added vertical lines at t=20000 to mark equilibrium
adjusted ylim vals for (c) and (d) and adjusted position of '(a)' and '(c)' labels
Merge branch 'master' of https://github.com/ahhurlbert/species-energy-simulation
changed input data files to those containing results from 100k time steps (instead of 30K), also adjusted xlim and x-axis of panel (c)