Add new Category key to FDF General Information section.

1. When D&D the FDF to Origin, FDF is automatically installed under the Categorys according to the Key.
2. If this new key is empty or missing, it will pop up dialog to ask about which category to install.
3. Operations in Fitting Function Builder and Fitting Function Organizer will update this Category key, such as Create/Move func.
4. Fitting Function Builder allow to change category since 2018.