After accepting #21 and #23 and releasing HeadShake, users reported that it didn't work with X-Camera anymore.

The reasons are:

1. Once HeadShake is overridden via the simcoders/headshake/override dataref, the head position datarefs are not updated anymore. I've fixed this with commit 7cd0b09.
2. The camera movements are now stuttering. I think this is caused by the "quantize" function. See this post: https://forums.x-plane.org/index.php?/files/file/20955-headshake-camera-plugin-lin-win-mac/&do=findComment&comment=279509

@quantumac I've reverted the changes on master and released v1.12.9 to make the stable release of HeadShake work again without issues with X-Camera.
Could you check these problems and make a new pull request? @markcellis is available for info about how the integration between X-Camera and HeadShake works.