Got the 2/3 factor for the low density problem, but gained an extra factor of theta:(

modified:   GNUmakefile
new file:   huang93Fig6sv.svg
modified:   ../myrefs.bib.in
modified:   ../phy452/basicStatMechProblemSet6Problem5.tex
modified:   ../phy452/mathematica/huang93relativisiticGas.nb
modified:   ../phy452/mathematica/negativeBinomial.nb