Support for filters with operands

First of all, thanks for this very useful module for storing user preferences, for example... (my use case).

But currently it does not support the use of filters with operands, like numeric ones with the operator is between, or others.

The values selected by the user for these filters are correctly stored in the database, but when they are retrieved again, they are not correctly stored in the proper #default key from the operands, so the user can not see them, and if he/she saves the edit form again, these previous values are lost.