Make sure to pass all variables defining the proper python version as found by
robotpkg, otherwise ros CMakeFiles may happily find python-3.2 and use it
instead of python<3, although this does not work in the end (at least ros-rx
does this and breaks on F17).

This is done in the common ros Makefile as this affects all packages.

The rx stack contains GUI-related tools for using ROS, including:

 . rxbag: ROS bag recording, playback and visualization

 . rxgraph: ROS graph visualization

 . rxplot: ROS topic data visualization

 . rxconsole: ROS/rosout logging output