This patch introduces tvg loader module for loading .tvg binary files.
This allows to load and reuse pregenerated scene.
tvg file format:
.tvg is a binary file format designed for saving/restoring the scene content.
It allows to save scenes and reuse them in other apps or to restore state of
the application.
@Example:
auto picture = tvg::Picture::gen();
picture->load(EXAMPLE_DIR"/tvg_file.tvg");
canvas->push(move(picture));
@API Additions:
Result paint(std::unique_ptr<Paint> paint) noexcept;
@Issue: Issue ticket is #375.
