Remove Corto filter FilterReservedMemberOfValues

[baszoetekouw]

The filter FilterReservedMemberOfValues is buggy and triggers the following exception:

Undefined array key 0 [/var/www/html/library/EngineBlock/Corto/Filter/Command/FilterReservedMemberOfValues.php:57]

However, we don't use this functionality any more, so let's just remove the entire filter.

[thijskh]

This can be removed as part of #1294.