LDAP nested groups patch (Copied from GeoffMaciolek:tkr-ldap-recurse pull #147)

[bpothier]

Copied from Pull request from GeoffMaciolek:tkr-ldap-recurse to see if it will merge
I ignored the "changed" lines in auth.php 622-626 and 628, removed blank line 678 from original patch as they appeared the same except likely some whitespace differences?
It now says able to merge...
You can try reverting those lines in @GeoffMaciolek / @trkr1410 's pull request to get it to merge?
Not sure if LDAP allows circular nesting, but I don't think the nested_groups() function checks for that.

[fgunger]

I see two problems with the proposed code:

1. There is a risk that LDAP may nest group membership circular and the function should to take this into account. (Needs to add a "max nesting" LDAP parameter or similar with a sane default.)
2. Groups search filter is also applied prior to checking for nested groups. So if you would set a "app-racktables"-filter, a group called "app-racktables-view" would not be found if the group membership would go though a "datacenter-technicians" group.
   I am afraid I won't have time to make the changes needed at the moment.