[Big] now user can delete files and folders and save clipped GPPK content

1) use "delete" option from contextmenu to delte files and folder
2) Click "Save" button under tree view and select file to save to. That way we can drastically chage file size and loading time it in seconds. (For example with only Data folder it occupies 15 Mb instead of 5Gb, has ~200 files instead of 140,000 and load in 1 second instead of 20-40 seconds)

Bugs:
- all content saved into clipped file as it is: no hashes are recalculated yet.
- deleting files need more testing