Bug in DES.c causing incorrect output

[rswjr]

In DES.c, line 296:
coordy += 2^(4 - jj);

This line seems to try to set the bit at position (4 - jj), but the caret symbol does not perform exponentiation in C. This is causing the program as written to produce the wrong ciphertext.

[mimoo]

good catch :) this is old code though, so I'm not going to fix it unless you want to submit a PR + some test vectors

[cmcqueen]

If you're going to share code, it is good to fix known bugs (regardless of whether the code is "old" or not).

[mimoo]

added the bug to the README