vtb: check and warn about non-2^n+1 size elevation before writing .chu
vtb: check and warn about non-2^n+1 size elevation before writing .chu

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