message-relay-procs: factor out subscription handling from bgdelivery and chat-procs and provide compatibility for streaming chat modes with HTTPS.
The message-relay-procs provide two different implementation for delivering messages to subscribers:
a) via bgdelivery (traditional method): this is, what was used so far, having the disadvantage that it only works on plain HTTP connections
b) via ns_connchan (new method): ns_connchan is a relatively new feature of NaviServer which allows transparent reading/writing from connections.
Chat has a new instance variable named "message_relay", which consists of preferences for the chat connections. So far, the traditional "bgdelivery" is still the default mode.
bumped version numbers - xotcl-core 5.10.0d14 - xowiki: 5.10.0d23