improve XYZ reader to guess float mode, use VTCompress in HGT reader
improve XYZ reader to guess float mode, use VTCompress in HGT reader

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