implement b2sum (#157)

README.md

@@ -52,7 +52,7 @@ compare against the true GNU coreutils version on the Linux-based tests first.
 | :-----: | --------- | ------------------------------------------------ |
 | ✓ | **[**     | Alternate form of `test`                         |
 | ✓ | arch      | Print machine hardware name                      |
-|         | b2sum     | Print or check BLAKE2 digests                    |
+| ✓ | b2sum     | Print or check BLAKE2 digests                    |
 | ✓ | base32    | Transform data into printable data               |
 | ✓ | base64    | Transform data into printable data               |
 | ✓ | basename  | Strip directory and suffix from a file name      |

src/b2sum/b2sum.v

@@ -0,0 +1,7 @@
+import common.sums
+import crypto.blake2b
+import os
+
+fn main() {
+	sums.sum(os.args, 'b2sum', 'Blake2', 512, blake2b.sum512)
+}