Cleaned up some stuff:
- there was some random unused interface in Simulation.java?
- the C_4TH_INVERSE_M_SQUARE_INVERSE force function incorrectly
calculated massstuff*r^(-2) + chargestuff*r^(-3), rather than -2 and -4.
oops. coefficients updated to keep things fun.
- added some potential energy stuff
Added some potential energy stuff. The plots are very insightful. And
confusing. I should probably test some of these numbers for accuracy.