Streamline file rename logic
Streamline file rename logic

- don't use a named block for renaming logic, make a sub for that
- don't use CATCH blocks
- don't do anything special for Windows, just always try 10 times
- throw Failure directly rather then depending on it being sunk
- make sure Failures are disabled to prevent warnings on DESTROY
- rename some variables to indicate their function

MasterDuke17/rakudo,rakudo/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tbrowder/rakudo,labster/rakudo,salortiz/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,labster/rakudo,salortiz/rakudo,salortiz/rakudo,labster/rakudo,rakudo/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tbrowder/rakudo,tbrowder/rakudo,tbrowder/rakudo,rakudo/rakudo,rakudo/rakudo,labster/rakudo,rakudo/rakudo,labster/rakudo,rakudo/rakudo,labster/rakudo,salortiz/rakudo