cipher: rename BlockDecryptMut::decrypt_padded_vec to decrypt_padded_vec_mut

[newpavlov]

It's a breaking change, but the method was introduced in today's release, so hopefully it will not affect anyone. I plan to yank cipher v0.4.1 to prevent further confusion.

[jcaesar]

You've managed to affect a crate and it's bitten someone. I'm not complaining, I'm just amazed.

I'll throw a PR to p12.

[newpavlov]

Oh, wow... Well, this is unfortunate. @Keruspe has submitted #936 to be used in p12, so no wonders it was used right away after cipher v0.4.1 was released. Unfortunately, it looks like he was offline when I wrote about the fix release.

[jcaesar]

Ah. And here I was wondering how that new function made it into other code so quickly. (Btw, the asker on Stackoverflow isn't exactly following best practice, and not using a lock file.)