Add hits associated to DT segments. Fix DT segments in RhoZ view, ...

...so that they are displayed aligned to 1D rechits.
The attached picture shows DTSegment with the fix (blue), overlaid to DT 1D rechits (yellow; displayed here just for reference)
![visdtsegments](https://f.cloud.github.com/assets/5168720/1350887/cf1184ba-3714-11e3-80b7-bfffa50f2521.png)