Change fluxSigma to fluxErr, apCorrSigma to apCorrErr and similarly for the diagonal elements of covariance matrices. This includes variable names, argument names and afw table field names. This is necessary in order to implement
Change afw::table::CovarianceMatrixKey to use "Err" as a suffix rather than "Sigma".
Update the FITS catalog persistence as follows:
- Bump the schema VERSION constant from 1 to 2 in SchemaImpl.h
- When reading version 1 catalogs make a fooErr as an alias to every fooSigma field
- When reading version 0 catalogs make Err aliases instead of Sigma aliases.