mod_rest/apidemo: Don't show traceback to users on config/resource problem

mod_rest: Add some notes about custom disco#info mapping code

mod_auth_cyrus: Adjust module import to work with repo clone - Fix #1744 The module import was made to work with the plugin installer, but was not compatible with the old method of cloning the whole repo

mod_http_admin_api: Indicate whether a given push registration uses encryption

mod_http_admin_api: Fix client -> client_id (the actual field name)

mod_http_oauth2/README: Update Compatibility section to mention 0.12

mod_rest: Add configuration of which stanzas to route to callback Makes it simpler to build APIs that only handle a certain kind of stanzas, letting them be handled by the unhandled stanza handler instead of having to write code to ignore certain kinds of stanzas.

mod_rest: Improve logging of results from callback startup probe Especially interested in logging 500 status codes and their errors, to diagnose problems with the callback API.

mod_rest: Support parameters in callback URL E.g. rest_callback_url = "http://myapi.example:5000/api/{kind}/{type}" which results in e.g. requests to /api/message/chat Allows using path routing in web frameworks for dispatch instead of having to pick apart the payload to further dispatch it.

mod_rest/README: Mention the OPTIONS probe fired at the callback ... in passing. Should be documented better. But not this day! This day, I commit features!