added removing of .gch files during make clean
added removing of .gch files during make clean

najoshi/sickle,kdmurray91/sickle,biorelated/sickle,MullinsLab/sickle,MullinsLab/sickle,ucdavis-bioinformatics/sickle,FabianFrancoRoldan/sickle,jdidion/sickle,MullinsLab/sickle