Allow edit and preview in separate windows

[neos-bot]

Jira issue originally created by user @hlubek:

Right now the edit, preview and UI settings are stored in the session (or at least globally). It's not possible to have one window or tab with an editing mode and one window with a preview mode open at the same time (unless the page is never reloaded). This is very annoying when testing JavaScript-heavy sites, where some scripts need the preview mode to test content changes. Besides that an editor or site integrator might want to choose that working mode instead of working in a single window.

We should find a way to use the window name to differentiate the browser windows or tabs.

Jira-URL: https://jira.neos.io/browse/NEOS-272

[mhsdesign]

This is still an issue btw.

And the Ui is not ready for that - eg when changing the edit mode in another tab, the global state changed and in the first tab the Ui still thinks one is in the previous edit mode and displays the switch accordingly - but the server responds with the new edit mode:

(i cannot select direct editing)

[mhsdesign]

The ui could hold the state in the local storage, and add it as param when requesting the preview