switched all code examples to WeatherPlay but text needs to be adapted/revised/extended

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@413 255f4249-2263-4417-b1ea-8498779e27a7
notes for general overview section

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@414 255f4249-2263-4417-b1ea-8498779e27a7
enabled multiway splits for categorical partitioning variables in mob()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@415 255f4249-2263-4417-b1ea-8498779e27a7
point out multiway splits in vignette

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@416 255f4249-2263-4417-b1ea-8498779e27a7