#9 Improve command, by telling that it is empty, when it is.
#9 Adds feedback, now within the command, before that was done in the
called player drop() / pick() method
#2 Returns an empty collecion, in case the incoming string of aliases is
empty or null.
#15 Now correctly visits the location storage instance
#15 Replaces call to player.print() with TextBuilderVisitor. Which shows
what the player is carrying.
#15 Updates Storage by holding the Item instances
#2 Small code improvements
#15 Clean up code