mod_s2s: Escape invalid XML in loggin (same way as mod_c2s) fix #1574

Merge 0.11->trunk

net.http: Add request:cancel() method This is a new API that should be used in preference to http.destroy_request() when possible, as it ensures the callback is always called (with an error of course). APIs that have edge-cases where they don't call callbacks have, from experience, shown to be difficult to work with and often lead to unintentional leaks when the callback was expected to free up certain resources.

net.http: Re-expose destroy_request() function This was accidentally turned private in 647adfd8f738 as part of refactoring for Lua 5.2+.

net.server_epoll: Log debug message when a connection errors on read It's confusingly quiet otherwise, even with maximum verboseness. Thanks perflyst

mod_register: Add a dependency on mod_watchregistrations Spammers are a big hassle, hopefully this will make admins aware of them sooner than when they’ve already spammed a bunch.

mod_proxy65: Limit dump of invalid data to 300 bytes (like mod_c2s)

mod_proxy65: Log invalid greetings escaped instead of as base64 Makes it easier to see human-readable parts and thus identifying the garbage. Also consistent with mod_c2s and others.

mod_server_contact_info: Add status-addresses field XEP-0157 version 1.1.0

configure: Pass compiler flag to enable ICU only when building util.encodings Passing it in CFLAGS applied to all modules, which was not needed.