renamed bithacks.h to popcount.h, some functions moved to imath.h
renamed bithacks.h to popcount.h, some functions moved to imath.h

fredwang00/primesieve,ZahidDev/primesieve,kimwalisch/primesieve,anatoliyrazin/primesieve,ZahidDev/primesieve,kimwalisch/primesieve,ZahidDev/primesieve,tempbottle/primesieve,tempbottle/primesieve,tempbottle/primesieve,kimwalisch/primesieve,anatoliyrazin/primesieve,anatoliyrazin/primesieve,fredwang00/primesieve,fredwang00/primesieve