(svn r2685) -Codechange: Split the music/sound/video drivers into separate files and move them into subfolders.

This results in shorter and hopefully easier to maintain files.
Note: I had to change paths in #include statements of some unrelated files, because I added the ottd base directory to the include path (-I.)

video/win32.h

@@ -0,0 +1,10 @@
+#ifndef VIDEO_WIN32_H
+#define VIDEO_WIN32_H
+
+#include "hal.h"
+
+bool MyShowCursor(bool show);
+
+extern const HalVideoDriver _win32_video_driver;
+
+#endif