Add `/.editorconfig`

## See: http://editorconfig.org/
> Please don't force end of line. 

I agree, users can just decide on their own  (__edit__: sorry for the repetition, I accidentally deleted my previous comment)

--

> SUPER annoying for windows users.

What @SBoudrias is referring to is that, by forcing `LF`, Windows users will get something like: 

```text
line▯line▯line▯line▯line▯
```

instead of 

```text
line
line
line
line
line
```

> eol normalization or sharing purpose is handled by git.

Unfortunately not all users use Git.