what happens if a kart already has a powerup when it hits a bous box:
you can get one more item of the same kind, one new item, or only one
more item if a random item is the same one as the one you currently have
(the latter being the old STK mode). stk_config.xml now sets 'new'
(always get a new randomly chosen item) as mode.
git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@6072 178a84e3-b1eb-0310-8ba1-8eac791a3b58