significant changes. style changes (no !, no =>). content additions. start by showing off R's non-programming features before getting to the language per se.
Fixed the mistake about integers that yuhui brought up. Deleted the confusing suggestion about command-enter (doesn't work for all GUIs or on Windows). Added some more information about vectors. Added some information about conditional clauses. Included some information at the very end on where to get R and R GUIs