Add to able to choose serialize/deserialize format

[aablinov]

Hello, what do u think about to add props to choose serialize/deserialize format? I think it's good practice serialize to JSON because it's more friendly to machine processing.

Something like this:

<Editor onChange=((value) => value('json')) serializeFrom={'json'} value={{JSON HERE}}/>

and need change in index.tsx function createState -> EditorState.fromJSON depending on settings.

[tommoor]

Markdown in + out is pretty much what makes this project unique – there are lots of prosemirror powered editors out there including the very pluggable remirror that enable this level of control…

Having said that it's not a huge lift and could be useful if it could be implemented quite seamlessly – serializeFrom probably not even needed just detect value if it's a string or an object?