Add more functions

Basic is basic, of course but it is just too basic.
- Ability to sort (filetype, name etc.)
- Export function as HTML, TXT etc. with individual selections (like specify filetypes that will be exported using wildcards)
- Screenshot feature
- Snapshot feature (make a snapshot of the actual state of the content, with individual choices)
- Use Snapshots to compare older/newer and vice versa Snapshots
- Better color schemes for different filetypes (customizable)
- Expand/Close all functionality for directories/folders and files
- Add customizable columns (date of creation, time etc.)