main content for mod2 close to being done for intro to R
broke ground on mod3 of intro to R
updates to conversion script -- still work to be done
swirl_out message when leaving swirl in 3 places in swirl.R: 2 in resume method and 1 in bye()

also replaced call to initial call to bye() in swirl()
 with call to removeTaskCallback so that exit msg in  bye wouldn't be printed