Provisional DTLS 1.2 support.

Add correct flags for DTLS 1.2, update s_server and s_client to handle
DTLS 1.2 methods.

Currently no support for version negotiation: i.e. if client/server selects
DTLS 1.2 it is that or nothing.
diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
index dbf790c..d8b9079 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -883,7 +883,7 @@
 
 	if (!ok) return((int)n);
 
-	if ( SSL_version(s) == DTLS1_VERSION || SSL_version(s) == DTLS1_BAD_VER)
+	if (SSL_IS_DTLS(s))
 		{
 		if ( s->s3->tmp.message_type == DTLS1_MT_HELLO_VERIFY_REQUEST)
 			{