v0.13.0

- Added favourite folders to organise your NATINF into nested folders;
- New “Folders” tab on the Favourites screen to browse, rename or delete folders and remove a NATINF from them;
- Personalise the app by choosing an alternate icon from the settings;
- Long-press the star on a NATINF sheet to add it to one or more folders or create a folder on the fly.
