Added better handling of NaN/0 pedigree to createensemble
Added better handling of NaN/0 pedigree to createensemble

Previously, createensemble didn't check that pedigree values made sense,
and 0s or NaNs could cause unintended results.  A NaN or 0 now indicates
that we want to keep a particular parameter as a point estimate.

kakearney/ecopathlite-pkg,kakearney/ecosystem-pkg,kakearney/ecopathensemble-pkg,kakearney/ecopathlite_2-pkg