This removes the requirement for `&mut self`s on some of the immutable
methods on `Automerge` which can be quite inconvenient.
I've reimplemented the main functions on `Automerge` that manipulate
state to create a transaction for their op for ease of use but not
performance. I've updated the edit trace to run in a single
transaction, like on a page load.
Wasm API still needs working on at the moment to expose this properly.
Rather than returning an OpID for every mutation, we now return an
`Option<ObjId>`. This is `Some` only when a `make*` operation was
applied. This `ObjID` is an opaque type which can be used with any
document.
Repeatedly setting the same value for a particular (obj, key)
combination now no longer generates an operation. To allow this we
modify the return value of `automerge::set` so that it may return an
`Option<OpId>` instead of an `OpId`.
Signed-off-by: Alex Good <alex@memoryandthought.me>
