Steady progress continues, today was mostly code refactoring but I also added few new features thanks to simpler code. Polygons can now be edited afterwards, though the feature is clumsy to use so definitely needs some refining. Also I just noticed there's sometimes memory corruption going on, no idea yet why but destroying and reloading the level seems to trigger it which causes weird behavior and crash. Also added camera controls so now it's possible to move around the world and zoom in/out in the level editor.