added todo.txt from https://piratenpad.de/p/rsjs595

review points 1 and 12

review point 2

review point 6

fix review point 7

fix review point 11

fix review point 8

fix review point 9

fix review point 10

fix review point 13

possibly uncaught errors seem to be caught after all (point 5)

repeat linkWidgetToSync once a second until it succeeds

fix widget sync button

don't enqueue push tasks for folders

delete todo.txt