screenshots data is now updated correctly
observe segmented control directly
added filename generation
moved value transformer into its own file
update metadata, when imageData is set
removed outlets, use binding. update actual image manually.
correctly format image size in b/kb/MB
create new screenshot object, if not existing
correctly set new screenshot
only initial option is needed
screenshot changes are correctly saved in group view controller
use placeholder image, if no image exists in bundle
use constants for KVO