checksumpackage: requires md5deep at least 4.4
checksumpackage: add _check_dfxml function
checksumpackage: add _version_dfxml function
checksumpackage: put local variables earlier
checksumpackage: add args -c -v -u and update usage
checksumpackage: apply new functions, improved logging, enact checks and verify options
checksumpackage: update to version 1.2