Add Option for MD5 checksum calculation and results in log (sf.net)

I have been using CH for a while now particularly when I am doing large amounts of copying/moving with large files (in the 10's to 100's of GB range), and have long wished that I could automatically have the results of an MD5 checksum comparison in the log, and in the case of a move if the checksums don't match for the original source file to not be deleted.

I once moved 500GB of files onto a new drive that was faulty and so I lost much of it.
(migrated from https://sourceforge.net/p/copyhandler/feature-requests/34/).