updated version number to 3.1
updated version number to 3.1

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