Closing issue "find a way around session cookies"

Two main things are done in the branch, firstly the session is being identified through a uid cookie. This one does not change upon reload, but f ex a new browser uses a new uid. This works with page reloads and connectivity issues. Also added an error, that indicates when the process is still running.

Also desynchronized the api endpoints and the backend. The reload cycle in the front end is 15s and 5s for the queue processor.

Generally errors are a bit more dynamic, added a "generic" key in the t_dict which if available displays whatever is stored in t_dict["generic"]. This allows for passing backend errors to the frontend long term, however most of the backend errors are "file not found" or exceptions because of None values which dont really tell the end user too much.