LDAP Sync User Settings

Dear,

I think it would be a nice feature to be able to prevent LDAP from overwriting settings that the user themselves have changed.
For example:
- User Language is set by LDAP's preferredlanguage tag. If the user changes their User Language then these changes get overwritten the next time GLPI syncs with LDAP.
- User has changed their e-mail address to that of a shared mailbox they are using so that everybody can see when they get an update on a ticket. But with a sync, these changes will be reverted.

Maybe a possibility to state that certain fields can only be overwritten during creation of the account, or always, or never. (last one might be a bit silly, but there might be some rare cases I guess).