The logic for `clone` which was updated to support cloning a viewed
document inadverantly left the heads of the cloned document state in
place, which meant that cloned documents could not be `change`d. Set
state.heads to undefined when cloning to allow changing them.
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.
Vite apps which use SharedWorker of WebWorker require additional
configuration to get WebAssembly imports to work effectively, add these
to the example.
Continuing our theme of treating all languages equally, move
wrappers/javascript to javascrpit. Automerge libraries for new languages
should be built at this top level if possible.
