random.nim: added shuffle proc; fixes 'mod' bias
random.nim: added shuffle proc; fixes 'mod' bias

russpowers/Nim,tulayang/Nim,tulayang/Nim,tulayang/Nim,dom96/Nim,dom96/Nim,russpowers/Nim,russpowers/Nim,dom96/Nim,dom96/Nim,tulayang/Nim,dom96/Nim,russpowers/Nim,tulayang/Nim,russpowers/Nim,tulayang/Nim,dom96/Nim,russpowers/Nim,dom96/Nim,russpowers/Nim