Breaking: Actions, Cookie Helpers, Loader and other API Changes

I'm using svemix in a few of my applications currently, i wasn't really happy with all apis, this should change some stuff and make it a little bit easier imo.

This PR changes a few things:

You now have access to parseCookies and makeCookie functions which is useful for handling cookies, under the hood it's using a version of the cookie package but rewritten in typescript. Also if you use sessions via handleSession the parsed cookies from handleSession get automatically passed on to locals which reduces overhead of parsing incoming cookies again.
You're no longer limited to the return types defined by svemix in actions, you can now return anything you like and can access the actionData even in Components, for Example in a NewPost Component, by today it wasn't easily possible to get the actionData without passing the props down. Here comes the new getActionData function, it uses sveltes getContext under the hood and returns an svelte store with your action data.
If you have sessions enabled they will now get fetched under /__session if the session updated in an action, so the client stays always in sync with the server and no refresh is required. You can also now pass you getSession function to handleSession, atm everything in the session get's exposed and you might want to have information in it that doesn't land on the client.
Loader API has changed a bit, you don't longer have to return {data: { foo: 'bar' }} instead you should directly return { foo: 'bar' }

Breaking:

You can now get your actionData by export let actionData in your svelte route components, via getActionData in children components of this route and via the <Form let:data let:submitting>, make sure you update everything accordingly, if you need help the docs should show some examples how it works.
You should rewrite all your loaders and remove the extra data property if you want to, otherwise make sure you have to use data.data everywhere.

pixelmund / svemix

Breaking: Actions, Cookie Helpers, Loader and other API Changes #39