Add `lang#s` and `lang#splus` layer
**What is language?**

The S programming language was developed in the late 1970s at Bell Laboratories. It was designed to be a statistical computing language that would make it easy to create statistical analysis software. S-PLUS is a proprietary version of the S language which was developed by Statistical Sciences in 1988 for use within their statistical analysis software packages.

**Which platform does the language support?**

- [ ] Linux
- [ ] MacOS
- [ ] Windows

**Any suggest vim plugins for this language?**


**Additional context**

