(svn r771) Do not give a file new {struct GRFFile} if it was already loaded once. Eliminates those double entries in the newgrf manager and also some possible memory leaks.
#ifndef SCREENSHOT_H
#define SCREENSHOT_H
void InitializeScreenshotFormats(void);
const char *GetScreenshotFormatDesc(int i);
void SetScreenshotFormat(int i);
bool MakeScreenshot(void);
bool MakeWorldScreenshot(int left, int top, int width, int height, int zoom);
#endif