Renamed the gp_*_bitmap classes to gp_*_image classes.
Added a first prototype/skeleton for the formatted_image<> class. Test-used it in the gp_image class.
Added the "gp_supported_pixel_formats" typedef, "roi" class, "desired_alignment" static constant and the current_image_type_id() member function as required by the formatted_image<> class.
Made the gp_image-from-IStream constructor public.
Removed some gp_image member functions that are now provided by the base class.
Renamed the gp_image::get_dimensions() member function to dimensions() to conform to the GIL image/view interface.
Added the first implementation of the view class for the gp_image class/backend.
Added Steven Watanabe's not-yet-official switch_ library to the detail folder as an internal implementation detail.
Removed some no-longer valid/relevant comments.
