make eqns 6 and 12+ more consistent; several small text tweaks
make eqns 6 and 12+ more consistent; several small text tweaks

pkgw/emcee,dfm/emcee,drphilmarshall/emcee,johnbachman/emcee,willvousden/emcee,willvousden/emcee,elkingtonmcb/emcee,ipashchenko/emcee-x,dfm/emcee,ga7g08/emcee,joezuntz/emcee,ipashchenko/emcee,dfm/emcee3,farr/emcee,jellis18/emcee3,johnbachman/emcee,linan7788626/emcee