improved safety checks in loadheaderfromgrid and create_culture
improved safety checks in loadheaderfromgrid and create_culture

seanisom/vtp,nakijun/vtp,markraz/vtp,nakijun/vtp,seanisom/vtp,seanisom/vtp,markraz/vtp,nakijun/vtp,seanisom/vtp,markraz/vtp,markraz/vtp,nakijun/vtp,nakijun/vtp,seanisom/vtp,markraz/vtp