from data can now be moved out (except music). STK prints
an overview of which directory is taken from where. More
cleanups and improvements will come.
Also moved skins into a separate directory under data (from
data/skins), since it's likely that skins will be part
of a binary package (i.e. changes to skins not really
related to code), while gui files will more likely stay
with the code.
git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@14731 178a84e3-b1eb-0310-8ba1-8eac791a3b58
