Pages: Remove unneedded backslashes.
Widgets: Add a standard checkbox widget.

Proper images still have to be made and addded.
Updater Models: Pass in Signal to use.

Also added minimum photo rating models to the factory.
Pages: Added minimum photo rating star toggles.
Misc: Added @todos.
Models: pylint fix.
Widgets: Add mouse events to headings.
Pages: Make Photo Edit and Settings same size.
Pages: Add a button to slide Edit Photo menu out.
Pages: Correct sizes in the Edit Photo panel.
Pages: Turn sliding menu into a macro.
Pages: Turn Photo Settings into a sliding menu.
Pages: Show Edit Photos menu by default.
PageManager: Remove reminders for non-existant bug
Timer: Single run timers not runnig once run.

The Timer should show itself as no longer running if it's only a single
run Timer that has called its function.
PhotoManager: Stop multiple bad cache calls.

The State Machine has been changed to only allow two bad cache calls
before idling. This also means that the PhotoManager needs an inital 1
second Timer to allow the DB facade time to start its thread etc.
Thread: Pause execution between job runs in thread
Settings: Save backups; load backup as failsafe.
Photo DB: Tidy member names, DB location passing.
ImageCache: Use Signal to pass screen size.