[improvement] Migrations (#217)

* Add better migrations

* Improves migrations

* rename dev to example

* renames migrate

* Removes workers from git

* Remove rogue dependency

* Fix dropdown navigation by keyboard

example/src/changing-id.tsx

@@ -0,0 +1,14 @@
+import * as React from 'react'
+import { TLDraw } from '@tldraw/tldraw'
+
+export default function ChangingId() {
+  const [id, setId] = React.useState('example')
+
+  React.useEffect(() => {
+    const timeout = setTimeout(() => setId('example2'), 2000)
+
+    return () => clearTimeout(timeout)
+  }, [])
+
+  return <TLDraw id={id} />
+}