(svn r10121) -Codechange: split renderer from rest of code; no longer any code directly accesses the video-buffer

-Add: added NULL blitter and renderer, which are always used for -vnull
-Add: dedicated driver doesn't blit nor render by default. Can be overruled by user. (-D -b 8bpp-optimized)
-Remove: removed CTRL+D from win32, which is incompatible with above
-Add: extended screenshot support for PNG and BMP
-Codechange: remove all hardcoded 8bpp references and replace them with more dynamic ones
-Codechange: minor stuff in blitters

src/renderer/null.cpp

@@ -0,0 +1,39 @@
+#include "../stdafx.h"
+#include "../gfx.h"
+#include "null.hpp"
+
+static FRenderer_Null iFRenderer_Null;
+
+void *Renderer_Null::MoveTo(const void *video, int x, int y)
+{
+	return NULL;
+}
+
+void Renderer_Null::SetPixel(void *video, int x, int y, uint8 color)
+{
+}
+
+void Renderer_Null::SetPixelIfEmpty(void *video, int x, int y, uint8 color)
+{
+}
+
+void Renderer_Null::SetHorizontalLine(void *video, int width, uint8 color)
+{
+}
+
+void Renderer_Null::CopyFromBuffer(void *video, const void *src, int width, int height, int src_pitch)
+{
+}
+
+void Renderer_Null::CopyToBuffer(const void *video, void *dst, int width, int height, int dst_pitch)
+{
+}
+
+void Renderer_Null::MoveBuffer(void *video_dst, const void *video_src, int width, int height)
+{
+}
+
+int Renderer_Null::BufferSize(int width, int height)
+{
+	return 0;
+}