Implement output in Unix-compatible hash utility format for validation

[kdevo]

Utilities such as sha256sum allow the validation of .<algorithm> (e.g. .sha256sum) files. These would be very useful as well as an export format as well as implementing a mechanism to validate existing files.

Example of output format:

98a862942edb350391637f416656e1071c111e590c4715175f6f5b47d4f579a7  *example.iso

Example argument in other command line applications (such as sha256sum):

  -c, --check          read SHA256 sums from the FILEs and check them