mod_muc_block_pm: Update to 0.12+ API, use roles instead of affiliations The module was possibly broken with 0.12 before. This changes the behavior to allow only messages to or from moderators.

This module blocks configured queries that change server state.

E.g. to make vCard storage read-only:

``` lua
readonly_stores = {
	vcard = { "vcard-temp", "vCard" };
}
```