fix coverity issue CID 10883
 fix few warnings
 remove unused variables
Coverity CID 10361 corrected by Sussana
remove data directory from macro in tutorial 4
restore the license text
correct typo in last commit
data directory does not exist when checking out a fresh copy of the software, this cause the tutorial 4 to crash. also te naming of the files is corrected to have the MC name in it.