GP name can be used).
2) Added support for challenges to be specified in .challenge files,
converted all existing challenges to be specified in this kind of
data file.
git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/trunk/supertuxkart@2188 178a84e3-b1eb-0310-8ba1-8eac791a3b58
