Make Mix (+) Mix about 1.5x faster
Make Mix (+) Mix about 1.5x faster

- also fix problem with negative weights cancelling out

Gnouc/rakudo,labster/rakudo,sjn/rakudo,usev6/rakudo,MasterDuke17/rakudo,usev6/rakudo,rakudo/rakudo,nbrown/rakudo,tony-o/rakudo,awwaiid/rakudo,raydiak/rakudo,rakudo/rakudo,salortiz/rakudo,tbrowder/rakudo,Gnouc/rakudo,sjn/rakudo,softmoth/rakudo,lucasbuchala/rakudo,jonathanstowe/rakudo,usev6/rakudo,awwaiid/rakudo,awwaiid/rakudo,rakudo/rakudo,tbrowder/rakudo,usev6/rakudo,MasterDuke17/rakudo,lucasbuchala/rakudo,raydiak/rakudo,softmoth/rakudo,Gnouc/rakudo,labster/rakudo,softmoth/rakudo,rakudo/rakudo,MasterDuke17/rakudo,lucasbuchala/rakudo,salortiz/rakudo,lucasbuchala/rakudo,sjn/rakudo,salortiz/rakudo,rakudo/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,tbrowder/rakudo,tony-o/rakudo,labster/rakudo,salortiz/rakudo,softmoth/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,salortiz/rakudo,Gnouc/rakudo,MasterDuke17/rakudo,jonathanstowe/rakudo,jonathanstowe/rakudo,jonathanstowe/rakudo,raydiak/rakudo,softmoth/rakudo,tony-o/rakudo,labster/rakudo,tbrowder/rakudo,labster/rakudo,nbrown/rakudo,jonathanstowe/rakudo,tony-o/rakudo,nbrown/rakudo,sjn/rakudo,nbrown/rakudo,awwaiid/rakudo,nbrown/rakudo,rakudo/rakudo,sjn/rakudo,tony-o/rakudo,tbrowder/rakudo,Gnouc/rakudo,tony-o/rakudo,usev6/rakudo,labster/rakudo,nbrown/rakudo,raydiak/rakudo,MasterDuke17/rakudo,awwaiid/rakudo,salortiz/rakudo