Add `/.editorconfig`

## See: http://editorconfig.org/
@alrra I don't think this is an issue you have to fix. If people in a company uses windows and commit with the same line ending, there's no issue, and if they have an issue, they'll find a solution fast enough.

Having worked on windows a lot in the last couples years, let each system uses it's own EOL and only normalize only when pushing to a remote.