mod_muc_markers: Add option for @id rewriting, default off (may break some clients) XEP-0333 was updated to clarify that stanza-id should be used instead of the 'id' attribute when in a MUC. Some clients still use the id attribute, which is why we were rewriting it. Rewriting is bad because mod_muc advertises stable_id, indicating that Prosody does *not* rewrite ids. Recent versions of Conversations actually depend on this being true. All clients should migrate to using stanza-id for markers. See XEP-0333.

# Introduction

This module adds a room configuration option to hide inline media from MUCs and
display them as links instead.

This can be useful in public channels where content posted by users should not
be shown by default.

# Configuring

## Enabling

``` {.lua}
Component "rooms.example.net" "muc"
modules_enabled = {
    "muc_hide_media";
}
```

## Settings

A default setting can be provided in the config file:

``` {.lua}
muc_room_default_hide_media = true
```