many changes and new features:
- set json/utf8 as standard for receiving and sending
- changed Models toJSON() to ignore null childs
- added import route in levelbuilder for data migration (previously openlevel)
- removed drafts for now, will come back later
- added a collection of all the current users levels to the levelbuilder start-view
- the level overview now fetches the levels from the server
- internal refactoring: views now have a standardized close method and can be either fullscreen or not fullscreen (true/false)
- new view function: onClosed, get called when a view is no longer rendered onto the screen (onClose gets called before it gets removed)
- level editor can now upload levels and edit already uploaded levels