Ported to m64.

I'm not sure about struct ClipRange. This struct gets size_t arguments (ctor, opIndex, opSlice) and it makes it incompatible with int in m64 version. One way is use toCairoCount, the second may be just make this struct get only int args instead of size_t? Then we don't hide from user that fact that cairo gets only int args and just let user to know this and handle it as it is?