[low priority] remaining links to migrate to nimterop org
followup after https://github.com/nimterop/nimterop/issues/105

README.md:
- [ ] `[![Chat on Gitter](https://badges.gitter.im/gitterHQ/gitter.png)](https://gitter.im/nimgen/Lobby)`
=> s/nimgen/nimterop/

- [ ] `[![Build status](https://ci.appveyor.com/api/projects/status/hol1yvqbp6hq4ao8/branch/master?svg=true)](https://ci.appveyor.com/project/genotrance/nimterop-8jcj7/branch/master)`
=> s/genotrance/nimterop/

- [ ] ditto with https://raw.githubusercontent.com/nimterop/wrappers/master/README.md
=> => s/genotrance/nimterop/

