Merge the engine branch into the main trunk. All conflicts resolved.

At the same time, add VMS support for Rijndael.

doc/apps/s_server.pod

@@ -39,6 +39,7 @@ B<openssl> B<s_server>
 [B<-hack>]
 [B<-www>]
 [B<-WWW>]
+[B<-engine id>]
 
 =head1 DESCRIPTION
 
@@ -186,6 +187,13 @@ emulates a simple web server. Pages will be resolved relative to the
 current directory, for example if the URL https://myhost/page.html is
 requested the file ./page.html will be loaded.
 
+=item B<-engine id>
+
+specifying an engine (by it's unique B<id> string) will cause B<s_server>
+to attempt to obtain a functional reference to the specified engine,
+thus initialising it if needed. The engine will then be set as the default
+for all available algorithms.
+
 =back
 
 =head1 CONNECTED COMMANDS