Async library, test programs and docs complete.

Author: peterhinch

README.md

@@ -232,8 +232,8 @@ Optional argument:
  the computation. This may improve application performance on slow platforms
  such as the ESP8266.
 
-For 9DOF sensors only: 
-``async def calibrate(stopfunc)``
+``async def calibrate(stopfunc)`` 
+For 9DOF sensors only.
 
 Argument:
  1. ``stopfunc`` Function returning ``True`` when calibration is deemed