Fixed bug in that format of the Python client's DATA command.

Python/src/xpc.py

@@ -124,7 +124,7 @@ class XPlaneConnect(object):
         if len(data) > 134:
             raise ValueError("Too many rows in data.")
 
-        buffer = struct.pack("<4sxB", "DATA", len(data))
+        buffer = struct.pack("<4sx", "DATA")
         for row in data:
             if len(row) != 9:
                 raise ValueError("Row does not contain exactly 9 values. <" + str(row) + ">")