Management configuration system

In the current state of the code, management screens can be configured through a configuration dialog, and such changes can be made persistent by saving them in the LDAP configuration node by users with enough rights (admin). Non-persistent changes are lost when leaving the management screen.

Problems, questions and ideas:

• It may be better if non-persistent changes were only lost at logout
• Users may want to have their own persistent changes? (Stored where? How to control such feature through ACLs?)
• Admins may want to offer pre-configured options to users (Stored where? Available how? ACLs? "Views"?)
• Configuration dialog should be easier to use and understand for non-expert users (Is there de-facto standards regarding column configuration out there?)
• What about filters, should we be able to add/remove some, or provide default values ? (I guess plugins should be able to add filters, maybe. Seems low prioriy anyway)

For selections screens, I think their changes should never be persistent. Not sure how filters and default columns should be computed.