Add .editorconfig and fantomas-config.json

[cmeeren]

Since Waypoint is opinionated regarding coding style, there should be an .editorconfig and a fantomas-config.json in the project root to make IDEs that support these files (e.g. VSCode, and VS at least supports .editorconfig) automatically use the correct settings.

[jbeeko]

added a basic .editorconfig in PR #5