New ctrls to retrieve supported signature algorithms and curves and
extensions to s_client and s_server to print out retrieved valued.

Extend CERT structure to cache supported signature algorithm data.
diff --git a/apps/s_client.c b/apps/s_client.c
index 7f38971..ce199be 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -2018,6 +2018,8 @@
 			BIO_write(bio,"\n",1);
 			}
 
+		ssl_print_sigalgs(bio, s);
+
 		BIO_printf(bio,"---\nSSL handshake has read %ld bytes and written %ld bytes\n",
 			BIO_number_read(SSL_get_rbio(s)),
 			BIO_number_written(SSL_get_wbio(s)));