HaikuDepot: Moved BitmapView into its own source file

 * Added BitmapButton, based on BitmapView, for clickable
   icons. Incomplete and untested.
HaikuDepot: BitmapButton fixes

 * BitmapView can be configured to scale or not to
   scale the bitmap.
 * BitmapButton more or less completed.
HaikuDepot: Vote up/down icons now clickable. Nothing happens.
HaikuDepot: Pargraph data classes for TextView

 * Added ParagraphStyleData. Contains actual style data. Incomplete.
   Supposed to be immutable,.
 * Added ParagraphStyle, references a ParagraphStyleData.
   Multiple ParagraphStyle object can refer to the same ParagrapgStyleData,
   when a style aspect is changed for ParagraphStyle, it makes its own
   copy of the previous ParagraphStyleData with the changed property.
 * Added Paragraph class, currently knows only its ParagraphStyle.
HaikuDepot: Added TextStyle convenience methods

 * Empty constructor
 * Copy constructor
 * operator==(const TextStyle& other)
HaikuDepot: Added TextSpan class
HaikuDepot: Paragraph holds TextSpan objects
HaikuDepot: Package status should come from PackageManager

 * But its unimplemented...
HaikuDepot: Added Insert() and Remove() to TextSpan.
HaikuDepot: TextSpan fixes for sometimes neglected fCharCount.
HaikuDepot: Added more methods to List

 * Add(ItemType, index) and Replace(ItemType, index)
HaikuDepot: Added Insert(TextSpan) to Paragraph