Style fixes, and fixes to improve conversion to notebooks

tutorials/fit/ConfidenceIntervals.C

tutorials/fit/line3Dfit.C

tutorials/fit/minuit2GausFit.C

tutorials/fit/multidimfit.C

tutorials/fit/myfit.C

tutorials/hsimple.C

tutorials/io/mergeSelective.C

tutorials/math/mathcoreVectorFloatIO.C

tutorials/math/principal.C

tutorials/math/testUnfold5c.C

tutorials/roofit/rf509_wsinteractive.C

tutorials/roofit/rf608_fitresultaspdf.C

tutorials/roofit/rf903_numintcache.C

tutorials/roostats/StandardHypoTestDemo.C

tutorials/roostats/Zbi_Zgamma.C

tutorials/tree/cernbuild.C

tutorials/tree/tree4.C