Checksum implemented

Output of help message


    $ ./dist/build/checksum/checksum --help            
    Shasum v0
    
    shasum [OPTIONS] [FILE]
    
    Common flags:
      -h --hashtype=sha1|sha224|sha256|sha384|sha512  Sha hash
      -c --check                                      read hash tags from file
                                                      and check them
      -? --help                                       Display help message
      -V --version                                    Print version information