Use same logic when determining when to expect a client
certificate for both TLS and DTLS.

PR#3452

The options which emulate a web server don't make sense when doing DTLS.
Exit with an error if an attempt is made to use them.

PR#3453

PR#3445

Add description of the option to advertise support of
Next Protocol Negotiation extension (-nextprotoneg) to
man pages of s_client and s_server.

PR#3444

This is actually ok for this function, but initialised to zero anyway if
PURIFY defined.

This does have the impact of masking any *real* unitialised data reads in bn though.

Patch based on approach suggested by Rich Salz.

PR#3415

PR#3440

  Detected by dcruette@qualitesys.com

Based on an original patch by Neitrino Photonov <neitrinoph@gmail.com>

PR#3439

PR: #3424,#3423,#3422

PR#2985

Based on feedback from Jeffrey Walton.

Reduces number of silly casts in OpenSSL code and likely most
applications.  Consistent with (char *) for "peername" value from
X509_check_host() and X509_VERIFY_PARAM_get0_peername().

PR#2277

PR: #3431

PR#3418.

Pass address of X509_VERIFY_PARAM_ID peername to X509_check_host().
Document modified interface.

Declaration, memory management, accessor and documentation.

PR#319 (reoponed version).

(cherry picked from commit 2cfbec1caea8f9567bdff85d33d22481f2afb40a)

Remove RFC5878 code. It is no longer needed for CT and has numerous bugs