bmap file integrity

[Razaloc]

Bmaptools checks the integrity of the bmap file before starting to copy.

Bmap-rs has the value bmap_file_checksum inside the Bmap struct but still does not check it. This is possible because there is a #[allow(dead_code)] flag in place.

[Razaloc]

On top of this, the bmap file can be signed using OpenPGP (gpg) and bmaptools automatically verifies the signature if it is present.

Edit: We are not that interested in this signature feature.