fusiontest.py minor fix. Part update README.md.

Author: peterhinch

README.md

@@ -95,7 +95,8 @@ The issue of the orientation of the sensor is discussed in
  1. `fusion.py` The standard synchronous fusion library.
  2. `fusion_async.py` Version of the library using uasyncio for nonblocking
  access to pitch, heading and roll.
- 3. `orientate.py` A utility for adjusting orientation of an IMU for sensor
+ 3. `deltat.py` Controls timing for above.
+ 4. `orientate.py` A utility for adjusting orientation of an IMU for sensor
  fusion.
 
 Test/demo programs:

fusiontest.py

@@ -6,6 +6,7 @@
 # V0.7 25th June 2015 Adapted for new MPU9x50 interface
 
 from machine import Pin
+import pyb
 import utime as time
 from mpu9150 import MPU9150
 from fusion import Fusion