[$] A new hash algorithm for Git

The Git source-code management system is famously built on the SHA"1hashing algorithm,which has become an increasingly weak foundation over the years. SHA"1 isnow considered to be broken and, despite the fact that it does not yet seemto be so broken that it could be used to compromise Git repositories, usersare increasingly worried about its security. The good news is that work onmoving Git past SHA"1 has been underway for some time, and is slowlycoming to fruition; there is a version of the code that can be looked atnow.