HaikuDepot: Disallow second split (package info) to collapse
HaikuDepot: Classes to interface with the Package Kit

 * Non functional
 * Basically allows to retrieve applicable actions for
   a given package.
HaikuDepot: Include star icon in resources
HaikuDepot: Include PackageManager.cpp in build
HaikuDepot: Class and method to retrieve a user rating summary
HaikuDepot: More work on package info view

 * Display rating via RatingView and additional BStringView
   decoration
 * Display radio buttons to switch between About, Ratings and
   Changelog pages. (Will be replaced again...)
 * Implement preliminary UserRatingsView showing all user
   ratings (currently in a single BTextView, will be much
   more detailed later on).
 * Implement ChangelogView, simply showing the dummy changelogs
   in a BTextView.
 * Layout tweaks