command_download: expose d.connection_[leech/seed](.set) to RPC interface

Apparently exposed "d.connection_current(.set)" command can't toggle initial seeding
mode. Ctrl-B uses "d.connection_seed.set=initial_seed", and that's the command that
truly works. As such, expose d.connection_[leech/seed](.set) so RPC users can use them.

Author: jesec

src/command_download.cc

@@ -1044,8 +1044,8 @@ initialize_command_download() {
                            std::placeholders::_1,
                            std::placeholders::_2));
 
-  CMD2_DL_VAR_STRING("d.connection_leech", "rtorrent", "connection_leech");
-  CMD2_DL_VAR_STRING("d.connection_seed", "rtorrent", "connection_seed");
+  CMD2_DL_VAR_STRING_PUBLIC("d.connection_leech", "rtorrent", "connection_leech");
+  CMD2_DL_VAR_STRING_PUBLIC("d.connection_seed", "rtorrent", "connection_seed");
 
   CMD2_DL("d.up.choke_heuristics",
           std::bind(&torrent::option_as_string,