(svn r75) -Add proper crediting to graphics artists to about box.

-Change DEBUG lvl for GRF warnings/errors to 2, lvl 1 is used for copyright notices
-Fix show currect filename when debugging grf files

spritecache.c

@@ -269,6 +269,7 @@ static void LoadGrfIndexed(const char *filename, const uint16 *index_tbl, int fi
 	int start;
 
 	FioOpenFile(file_index, filename);
+	_cur_grffile = filename;
 
 	for(;(start=*index_tbl++) != 0xffff;) {
 		int end = *index_tbl++;