Setting up a robot

Adopted Carina's work with @doudou's comments. Could not resolve everything, but at least her effort is not in vain...
Have you ever seen someone change directories within a Rock system ? Using auto-completion is actually NOT a very common occurence, which means that actually typing the command with the env var is for most people as long as using acd. I am *not* kidding or exagerating. Especially since acd does some autocompletion of his own (e.g. d/o/sonar_trit will resolve to drivers/orogen/sonar_tritech) and is independent of *where* the package is. This is acd PACKAGE_NAME not acd DIRECTORY.

The fact is: people do use acd (or nobody would have noticed that it was broken), which means that they do find a benefit to it. "Advanced users" don't need to have their hands held to tell them how best to change directories.

As for the speed, yes, I know, I need to find time to release the next autoproj version.