Add several more default cipher algorithms and make initialization with an EVP_CIPHER public

[MrMage]

See #59 for discussion. I have not deprecated any of the existing ciphers without further discussion. Note that the new ciphers are unsafe to use without a 128-bit initialization vector.

Regarding making init(c: UnsafePointer<EVP_CIPHER>) public: I had issues using Cipher(named: "aes-256-cfb") on Linux — the cipher was not found. Using EVP_aes_256_cfb128() worked, however. If this is the case for other ciphers as well, it makes sense to let users pass in any EVP_CIPHER they'd like instead of having to refer to them by name.

[MrMage]

I'm starting to get the suspicion that AES-CFB is not supported on my Linux base image (Ubuntu 14.04). However, it might be supported (and desired) on other systems, and AES-CBC works even on my system.

[tanner0101]

I don't have a problem with init(c: UnsafePointer<EVP_CIPHER>) being made public. It's not really worth keeping the fact that this implementation is based on OpenSSL a secret. If we were to ever switch away from OpenSSL, it would be a breaking change anyway.

[tanner0101]

@MrMage would you want to add the deprecations for the old ECB code to this PR? As discussed in #59

[MrMage]

I have added deprecations, comments, and global constants. Please take another look.

[MrMage]

Friendly ping :-)

[tanner0101]

thanks!

[penny-coin]

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