8.0: Try libvips

[jurplel]

prototype made in #802. We'll see how it goes

[jurplel]

Can get EXIF data with this, e.g.

int orientation = image.get_int("exif-ifd0-Orientation");
std::vector<const char *> fields = image.get_fields();

[jurplel]

Memory usage is very high. maybe a leak. i also saw a crash while switching images.