Refactor the "for range/sequence { }" optimization
Refactor the "for range/sequence { }" optimization

- generalize it to a flexible step
- less mixing up of what's the start and end of the loop
- should make it easier to allow for "for 1,3...10 { }" optimization

softmoth/rakudo,MasterDuke17/rakudo,tony-o/rakudo,tony-o/rakudo,softmoth/rakudo,salortiz/rakudo,rakudo/rakudo,softmoth/rakudo,salortiz/rakudo,rakudo/rakudo,rakudo/rakudo,Gnouc/rakudo,nbrown/rakudo,nbrown/rakudo,labster/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,labster/rakudo,tbrowder/rakudo,salortiz/rakudo,softmoth/rakudo,Gnouc/rakudo,tony-o/rakudo,labster/rakudo,rakudo/rakudo,labster/rakudo,nbrown/rakudo,tony-o/rakudo,Gnouc/rakudo,Gnouc/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,labster/rakudo,MasterDuke17/rakudo,tony-o/rakudo,salortiz/rakudo,softmoth/rakudo,nbrown/rakudo,rakudo/rakudo,salortiz/rakudo,labster/rakudo,tony-o/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,salortiz/rakudo,tbrowder/rakudo,Gnouc/rakudo,tbrowder/rakudo,nbrown/rakudo,nbrown/rakudo,tbrowder/rakudo,rakudo/rakudo