speed up of EratBig.cpp -> lower limit EratMedium.cpp
speed up of EratBig.cpp -> lower limit EratMedium.cpp

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