add dirt/samples directory to path

[guaka]

I got some errors about dirt not being able to find samples/bd and samples/sn.
Now I'm starting it like this:

pushd ~/dirt; ./dirt&
popd

It would be nice if dirt could find its own samples directory regardless from where it was started.

[yaxu]

Or maybe the samples folder should be specifiable on the commandline?

[guaka]

-s|--samples-path is nice but both would be best. Actually I see three possibilities:

1. use samples-path if it's set
2. check cwd (and subdirs) for existence of usable samples, use this if yes
3. find location of dirt and use that as fallback