Fix cppchecker warnings

src/Afterburner.cc

src/Arithdays.cc

src/Cat.cc

src/Collgrid.cc

src/Copy.cc

src/DCW_util.cc

src/Detrend.cc

src/Diff.cc

src/Distgrid.cc

src/Echam5ini.cc

src/Ensval.cc

src/Exprf.cc

src/Fldstat.cc

src/Gridsearch.cc

src/Healpix.cc

src/Importbinary.cc

src/Importcmsaf.cc

src/Info.cc

src/Input.cc

src/Intgrid.cc