Merge SSLv23_method and DTLS_ANY_VERSION.

This makes SSLv23_method go through DTLS_ANY_VERSION's version negotiation
logic. This allows us to get rid of duplicate ClientHello logic. For
compatibility, SSL_METHOD is now split into SSL_PROTOCOL_METHOD and a version.
The legacy version-locked methods set min_version and max_version based this
version field to emulate the original semantics.

As a bonus, we can now handle fragmented ClientHello versions now.

Because SSLv23_method is a silly name, deprecate that too and introduce
TLS_method.

Change-Id: I8b3df2b427ae34c44ecf972f466ad64dc3dbb171
22 files changed