Add access to internal accelerations

Add access to the accelerations values from the internal tilt state.
This commit uses freenect_get_mks_accell driver call.

Extracting the (x, y, z) values from the driver seems to be a little
messy due to some low-level conversion. But it works :]
Add stop functions for video and depth streams

Just add the missing stop functions for the video and depth streams
Fix typo in subdevice datatype

The third flag is called Audio :)
Add support for kinect's microphones

Add libfreenect_audio.h functions to the haskell interface.
Merge pull request #9 from ruuns/master

Add access to internal accelerations