New branch open: v3.1 (first-class documents)

[Marijn Haverbeke]

Hi list,

I've just pushed the first public version of the first-class document
overhaul. See the thread at [1] for background. In the v3.1 branch on
the github repository, which is checked out at [2], there are the
following new features:

- Create documents without editors
- Change the document that an editor is currently showing
- Create linked instances of a document, which automatically stay in
sync with their parent (for split views, see [3] for a demo).
- Create linked sub-views on a document (smaller documents which are
kept in sync with the part of the parent document that they refer to)
- Two models of handling history for linked documents: shared and separate

Find the docs for most of these new features at [4].

A lot of rewriting and re-engineering was needed to support this
model, so without a doubt new defects were introduced. If you're
interested in these features, please test, so that we can make this
into a stable 3.1 release soon. The API is backwards-compatible with
3.0.

The v3.1 branch will be shamelessly rebased in the near future, so
don't count on its commits being stable just yet.

[1]: https://groups.google.com/d/topic/codemirror/euMAHMBq6IM/discussion
[2]: http://codemirror.net/3.1/
[3]: http://codemirror.net/3.1/demo/buffers.html
[4]: http://codemirror.net/3.1/doc/manual.html#api_doc

Best,
Marijn