photocam should reset its preload when a new file is loaded
photocam should reset its preload when a new file is loaded

this prevents infinite busy animations

@fix

tasn/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,FlorentRevest/Elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,rvandegrift/elementary,rvandegrift/elementary,FlorentRevest/Elementary