daeger eit load offset error, add offset 8->16

Author: liubenyuan

pyeit/io/daeger_eit.py

@@ -76,7 +76,7 @@ def read_header(fname, max_lines=50):
         with open(fname, "rb") as fh:
             b = fh.read(16)
             a = struct.unpack("8H", b)
-            offset = a[2] + 8
+            offset = a[2] + 16
 
         # number of frames
         nframe = int((flen - offset) / spc)