update sequest algorithm to use Data.Vector
update sequest algorithm to use Data.Vector

Ignore-this: e1bc3d7aba89743ac7154deeb30ec7b8

darcs-hash:20100224124129-9241b-1b0b35b48e684a86488a214e4c8e643a2fa14555.gz

tmcdonell/hfx,tmcdonell/hfx,tmcdonell/hfx