Make it easy to tell if a unit is kneeling by changing the arrow

It's hard to tell sometimes if a unit is kneeling or not. This changes the shape of the arrow above their heads if the unit is kneeling. It also creates a more smooth arrow bob
![avsyni6](https://cloud.githubusercontent.com/assets/312503/3174942/a1c00ea4-ebf6-11e3-95d9-909011fe9374.png)