Return current position for python 3.x compat

Author: dgburr

kaitai/python/kaitai_sbp/parse_utils.py

@@ -36,6 +36,7 @@ def seek(self, offset, whence=SEEK_SET):
                 self.pos += offset
             elif whence == SEEK_END:
                 self.pos = len(self.buf)
+            return self.pos
 
         def tell(self):
             return self.pos