Version color visibility in gantt
First of all, thank you for the nice theme!

The problem is that version lines are rendered with white color in gantt, which is hard to be recognized.
Also, the end marker is not visible.
![minimalflat2](https://cloud.githubusercontent.com/assets/238681/23491465/d8558064-ff41-11e6-830c-6c3df48ca881.png)

Here is the same gantt with Default theme.
![defaulttheme](https://cloud.githubusercontent.com/assets/238681/23491544/3b65842e-ff42-11e6-8f25-1c8f558a45e8.png)