code: Add openssl BIO datetime server example.
code: Hardcode args in openssl BIO client example
code: Properly shutdown BIO daytimeserver conns.

First call to BIO_do_accept() calls listen(2). Succeeding ones invokes
accept(2). Not intuitive!
code: Add openssl BIO echo server/client.

I've tried to keep the examples short; I rely on the OS for cleaning up
allocations, and am somewhat sloppy about error handling for puts/gets calls.
code: Add .gitignore for openssl/bio.