The API of Automerge::generate_sync_message requires that the user keep
track of in flight messages themselves if they want to avoid sending
duplicate messages. To avoid this add a flag to `automerge::sync::State`
to track if there are any in flight messages and return `None` from
`generate_sync_message` if there are.
Generating patches to text objects (a la the edit-trace benchmark) was
very slow due to appending to the back of a Vec. Use the SequenceTree
(effectively a B-tree) instead so as to speed up sequence patch
generation.
Sometimes you need a cheap copy of a document at a given set of heads
just so you can see what has changed. Cloning the document to do this is
quite expensive when you don't need a writable copy. Add automerge.view
to allow a cheap read only copy of a document at a given set of heads
and add an additional heads argument to clone for when you do want a
writable copy.
After some discussion with PVH I realise that the repo structure in the
last reorg was very rust-centric. In an attempt to put each language on
a level footing move the rust code and project files into ./rust
