Initial support of Multi Valued Attributes operators

[Arran Cudbard-Bell]

>> For example, this will allow to simply check ldap-group with unlang
>> without building a foreach loop or using huntfile. Arran is in the
>> process to add this feature to rlm_ldap.
> 
> Again, I don't understand this; this is what "Ldap-Group == xx" already doesn't it? Have I misunderstood?

The feature i'm adding doesn't depend on these operators. The LDAP-Group paircomp function will loop over cached group attributes without the new operators. This is required to emulate behaviour where the check is being performed directly against directory.

-Arran