Fix bug for asymmetric uncertainties with scaling modifier. E.g use bla:A+ bla:A- format to make asymmetric source bla additive and not  bla+:A bla-:A for now.

git-svn-id: https://svnsrv.desy.de/basic/h1fitter/trunk@1571 b2a8d302-ca0a-427a-b7b9-081adbce06bc
pdf uncertainties treated as additive in D0 W asymmetry



git-svn-id: https://svnsrv.desy.de/basic/h1fitter/trunk@1572 b2a8d302-ca0a-427a-b7b9-081adbce06bc