#1112 [WIP] Feature/item persister and retriever (state: open)

Description

This feature extracts the database interfacing routines into separate classes.

This is currently work in progress.

Checklist

• [X] Read and understood the CONTRIBUTING guidelines
• Created tests, if possible
• All tests passing
• Extended the README / documentation, if necessary
• Added myself to the @authors in touched PHP files
• Checked the changes with phpcq and introduced no new issues

we might want to cherry-pick 2798cd655a36a431dbb12401336582aa8d718d52 here.

• Update or New and save item at BE: works fine

test for https://github.com/MetaModels/core/issues/1005 with translated_text: the empty "zomby cells" live on

=> "check the value and delete"

Change base branch and reopen?

Something else to do here, we should inject the persister, retriever and resolver via constructor injection. That way the MetaModel will become more independent and we could swap either component by another one (using doctrine connection i.e.) in the future.

Why closed?

I deleted the alpha17 branch and github closed the PR then. :/

o.k.