This is a work-in-progress to create a consistent API and finally
separate the whole Aseprite base/gfx/ui libs into a reusable C++ library.
Classes:
app::IFileItem, app::AppMenuItem, app::skin::SkinPart,
gfx::Rect, gfx::Border, she::FileDialog,
ui::IButtonIcon, ui::Graphics, ui::Overlay, ui::Widget,
ui::ScrollableViewDelegate, and UI events
Changes:
* Create render library (move util/render.cpp to render/render.cpp)
* Move app::Zoom class to render::Zoom
* Remove doc::Image::merge() member function
* Add gfx::Clip helper class (to clip dst/src rectangles before a blit)
* Move doc::composite_image() to render::composite_image()
* Remove doc::Sprite::render()
* Replace Sprite::getPixel() with render::get_sprite_pixel()
* Remove doc::layer_render() function
* Convert DitheringMethod to a enum class
* Add AppRender to configure a render::Render with the app configuration
* Move checked background preferences as document-specific configuration
* Add doc::Sprite::layer() and palette() member functions
* Add doc::Layer::cel() member function
* Add doc::Palette::entry() member function()
* Add doc::frame_t type
* Move create_palette_from_rgb/convert_pixel_format to render library
* ExportSpriteSheet doesn't need a temporary image now that we can specify
the source rectangle in the render routine
Before the zoom was handle as a bits shift (scaled = value << zoom),
now the zoom is a fraction (scaled = value * zoom.num / zoom.den).
Changes:
* Add Zoom class to apply/remove zoom factor
* Split merge_zoomed_image template function into
merge_zoomed_image_scale_down and merge_zoomed_image_scale_up
to handle the special case where zoom.num/zoom.den < 1.0
Changes:
* Add doc::Sprite::bounds()
* Use gfx::Point to store the doc::Cel position
* Replace "int x, int y" with a "const gfx::Point&" param
* Fix Mask::intersect(const gfx::Rect&) and Mask::crop(const Image*)
