add  https://github.com/xujiajun/gotokenizer  library (#2160)
add  https://github.com/xujiajun/gotokenizer  library (#2160)

Please check if what you want to add to `awesome-go` list meets [quality standards](https://github.com/avelino/awesome-go/blob/master/CONTRIBUTING.md#quality-standard) before sending pull request. Thanks!

**Please provide package links to:**

- github.com repo: https://github.com/xujiajun/gotokenizer
- godoc.org: https://godoc.org/github.com/xujiajun/gotokenizer
- goreportcard.com: https://goreportcard.com/report/github.com/xujiajun/gotokenizer
- coverage service link: https://coveralls.io/github/xujiajun/gotokenizer?branch=master


Very good coverage

**Note**: that new categories can be added only when there are 3 packages or more.

**Make sure that you've checked the boxes below before you submit PR:**
- [✔️ ] I have added my package in alphabetical order.
- [✔️ ] I have an appropriate description with correct grammar.
- [✔️ ] I know that this package was not listed before.
- [✔️ ] I have added godoc link to the repo and to my pull request.
- [✔️ ] I have added coverage service link to the repo and to my pull request.
- [✔️ ] I have added goreportcard link to the repo and to my pull request.
- [✔️] I have read [Contribution guidelines](https://github.com/avelino/awesome-go/blob/master/CONTRIBUTING.md#contribution-guidelines), [maintainers note](https://github.com/avelino/awesome-go/blob/master/CONTRIBUTING.md#maintainers) and [Quality standard](https://github.com/avelino/awesome-go/blob/master/CONTRIBUTING.md#quality-standard).

Thanks for your PR, you're awesome! :+1:

jmelfi/awesome-go,sadlil/awesome-go,avelino/awesome-go,pconcepcion/awesome-go,Oire/awesome-go,theckman/awesome-go