mod_adhoc_dataforms_demo: Fix duplicate field prevention It's supposed to only include each type of form field once per form at most but it didn't note which fields it had added already. No idea what the probability was anyways, probably pretty low.

This module blocks configured queries that change server state.

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

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