Revert "Revert "BackendModel::deleteExtraById can now delete blocks.""
Revert "Revert "BackendModel::deleteExtraById can now delete blocks.""

This reverts commit 5a767a88a43f55feaaa307fc6b1cbc06b07bca1e.

justcarakas/forkcms,mathiashelin/forkcms,sumocoders/forkcms,riadvice/forkcms,carakas/forkcms,ikoene/forkcms,jacob-v-dam/forkcms,vytenizs/forkcms,jonasgoderis/jonaz,vytsci/forkcms,jonasgoderis/jonaz,Thijzer/forkcms,WouterSioen/forkcms,justcarakas/forkcms,lowiebenoot/forkcms,Saxithon/gh-pages,ikoene/forkcms,vytsci/forkcms,riadvice/forkcms,DegradationOfMankind/forkcms,Katrienvh/forkcms,forkcms/forkcms,vytenizs/forkcms,jessedobbelaere/forkcms,sumocoders/forkcms,jonasgoderis/jonaz,Thijzer/forkcms,mathiashelin/forkcms,carakas/forkcms,jonasdekeukelaere/forkcms,nosnickid/forkcms,dmoerman/forkcms,jacob-v-dam/forkcms,vytsci/forkcms,jonasdekeukelaere/forkcms,jonasdekeukelaere/forkcms,jonasgoderis/jonaz,matthiasmullie/forkcms,forkcms/forkcms,gertjanmeire/davy_portfolio,sumocoders/forkcms,dmoerman/forkcms,tommyvdv/forkcms,riadvice/forkcms,jessedobbelaere/forkcms,jeroendesloovere/forkcms,Katrienvh/forkcms,wengyulin/forkcms,jeroendesloovere/forkcms,Katrienvh/forkcms,tommyvdv/forkcms,riadvice/forkcms,dmoerman/forkcms,jonasgoderis/jonaz,wengyulin/forkcms,tommyvdv/forkcms,jacob-v-dam/forkcms,Saxithon/gh-pages,Katrienvh/forkcms,jessedobbelaere/forkcms,matthiasmullie/forkcms,bartdc/forkcms,carakas/forkcms,ocpyosep78/forkcms,forkcms/forkcms,WouterSioen/forkcms,jonasdekeukelaere/forkcms,jacob-v-dam/forkcms,wengyulin/forkcms,ikoene/forkcms,gertjanmeire/davy_portfolio,nosnickid/forkcms,sumocoders/forkcms,matthiasmullie/forkcms,vytenizs/forkcms,lowiebenoot/forkcms,sumocoders/forkcms,bartdc/forkcms,DegradationOfMankind/forkcms,jeroendesloovere/forkcms,carakas/forkcms,Thijzer/forkcms,nosnickid/forkcms,jonasdekeukelaere/forkcms,jessedobbelaere/forkcms,ocpyosep78/forkcms,carakas/forkcms,mathiashelin/forkcms,DegradationOfMankind/forkcms,forkcms/forkcms,justcarakas/forkcms,bartdc/forkcms,mathiashelin/forkcms,jeroendesloovere/forkcms,DegradationOfMankind/forkcms,tommyvdv/forkcms