ddraw: Separate reference counting for IDirectDraw7 and IDDS4 from IDDS3, IDDS2 and IDDS (try 2)

[Stefan Dösinger]

I think it is better to separate the vtables first - ie, give  
IDirectDrawSurface4,  IDirectDrawSurface2 and IDirectDrawSurface their  
own vtable

Also the last iteration of Michael Karcher's patches missed out some  
getters, like IDirect3DDevice*::GetRenderTarget. There may be other  
functions that need to be adjusted to AddRef/Release version specific  
refcounts.