Style line arrows and line dots differently.

Currently the line arrows and dots are the same color and style.

Distinguish between the two visually. Suggestion: make the dots grey(?)

![screen shot 2014-09-18 at 1 49 35 pm](https://cloud.githubusercontent.com/assets/1521387/4319263/2063263e-3f2a-11e4-8e19-51aaf803d7a4.png)