Development

fixes #133:
- determine metadata of resources (images, sounds, files, directories)
- show/hide details in MyProgramsViewController
- show/hide details in ProgramTableViewController
- show/hide details in LookTableViewController
- show/hide details in SoundTableViewController
- use NSUserDefaults to remember user preferences
- minor performance optimizations (data-cache for details of TableViewCells)
- use dequeueReusableCellWithIdentifier:forIndexPath: method instead of older dequeueReusableCellWithIdentifier: method in all TableViewControllers