mod_muc_limits: Add config option to limit to join stanzas only This is a bit more limited in pre-0.11 MUC modules, because it just detects stanzas sent to full JIDs (which would include all presence and nick changes). This option is useful for setups where users are typically unaffiliated, but trusted (e.g. if access to the room is gated through some other means such as password/token auth).

# Introduction

This module sends a [version query][xep0092] to clients when they
connect, and logs the response, allowing statistics of client usage to
be recorded.

Note that since this is per connection, there will be a bias towards
mobile clients on bad connections.

## Example

    info    Running Running Swift version 4.0