using observations and gmix lists
adapting to new system
new modules
more restructuring
getting psf flux fitting on new system
getting psf flux fitting on new system
docs
working on combined priors
working on combined priors
factoring out pqr calculation
factoring out pqr calculation
factoring out pqr calculation
working with new style
added get_nuse method
docs
fixed bug in calc_result where weights were not being applied
define Chain class
 docs
Merge branch 'obs' of github.com:esheldon/ngmix into obs
updated jacobian to allow setting cen.  observation now takes an Observation for psf