Use the metadata flag that gives a smaller file

In earlier versions, you had to choose whether keeping or discarding the metadata. If you don't matter about that and you just want smaller files, now you can leave that decision to SlimJPG. It will try both methods and give the smaller picture possible.

By the way, don't use this release. We tried it on production and it had an issue with files with corrupted Huffman Codes table. If you don't know what's that, just use 1.3.1 😅

Oh, it's shame time: in some strange cases, it could lead to an infinite loop. We hadn't been able to reproduce with tests, because it happened in production with a picture of one of our lovely users, but it happened.