Fix various issues with Str.(lines|words)($limit)
Fix various issues with Str.(lines|words)($limit)

Original code predated the existence of .head.  Both forms of calling
.lines and .words on Str should now return .Seq and be properly lazy.

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