K1 turtle: add dots every 50px

- Change dropdown images to include dots

![image](https://cloud.githubusercontent.com/assets/206973/3771638/1fff3d1c-18f7-11e4-85de-35e92edb921d.png)

![image](https://cloud.githubusercontent.com/assets/206973/3771772/69800308-18f8-11e4-8e18-67084651af25.png)

Not in the current k1 curriculum. The thought was "in case" line width adjustment gets later enabled, this would be a better behavior.

I'm actually going to be switching the joint drawing to be a drawArc call next, so I'll change it to an absolute radius.