I tried this package and it worked.Just
set working dir to where the 2 files are located,and type ">help limitcycleplot".
I have to say Vande Pol is perfect example
in this case.Try E=1/2 x^2 + 1/2 y^2 and
you will NOT get a closed orbit but a growing
helix(maybe this is due to inevitable numerical error).Try a few other system
that has critical points and the program
cannot successfully pass a separatrix.