Introduce aliases. These are used for Search.
Aliases are stored in Z2K4. They are stored as a set of monolingual labels, but unlike the ones in Z2K3 there can be more than one.
No value that is a label should be an alias for the same language for the same object.
No alias should appear twice for the same language and object.
An alias can be the same as a label or an alias on another object, even with the same types and languages.
This task will probably require to change the wikilambda_zobject_labels table regarding the uniqueness constraint on wlzl_label_unique, It might also need to introduce another field for the unnormalized alias.