Hint, Info, Warning should be sent to stderr

```bash
$ nimble path AntTweakBar                                                                                                          
       Info Hint: used config file '/home/arne/proj/nim/Nim2/config/nim.cfg' [Conf]
   Warning: Package 'fancygl' has an incorrect structure. It should contain a single directory hierarchy for source files, named 'fancyglpkg', but file 'testmain.nim' is in a directory named 'unittests' instead. This will be an error in the future.
      Hint: If 'unittests' contains source files for building 'fancygl', rename it to 'fancyglpkg'. Otherwise, prevent its installation by adding `skipDirs = @["unittests"]` to the .nimble file.
/home/arne/.nimble/pkgs/AntTweakBar-1.0.0
$ cd `nimble path AntTweakBar`                                                                                                         
cd:cd:6: too many arguments
```

actually this is a requirement for me, because I rely on nimble path to output only the path here:
https://github.com/krux02/nimAntTweakBar/blob/master/AntTweakBar.nim#L25