Editor Preview

[Zini]

We are getting close to the point, where we can show the editor to the public. Not in the form of a release, but either as part of a release video or a separate video (2nd option makes more sense IMHO).

There are a few tasks that need to be completed first:

* Editor: User Settings (done, but unfortunately it needs a partial rewrite)
* Editor: Start Dialogue (currently we have a minimal placeholder implementation)
* Editor: Handle document closing (done)
* Editor: Display record state as an icon instead of a number (done)
* Editor: drag & drop of sub views between top level windows of the same document
* Modify ESX selector to handle new content file scheme
* Editor: configuration setup
* Editor: Adjust name/path of edited content files

Not strictly necessary, but still nice to have:

* Editor: Display record type as an icon instead of a number (done)

If we don't get this feature, we can replace the numbers with text instead. Ultimately we want this to be configurable via user settings (text only, icon only, text and icon).

I am going to keep this first posting updated as we make progress.