found that some non-fixed-length header DEMs break all existing tests, implemented a sliding scan to find start of DEM B record
found that some non-fixed-length header DEMs break all existing tests, implemented a sliding scan to find start of DEM B record

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