Add .inc files to editorconfig
Add .editorconfig file
To start with just `.php` files. According to the [Developer Style Guide](https://doc.pfsense.org/index.php/Developer_Style_Guide):
- Use tabs for indentation (not spaces or a mixture of both)- Use a tab stop of 8, rather than 4- Ensure there is NO trailing whitespace at the end of a line, for example spaces or tabs when there is no more text afterward...