Empty final columns cause endOfInput errors for Maybe values

[axman6]

When the final column of a cvs may be empty, decodeByName fails with an endOfInput error when the column is of type Maybe a.

...,1-2,5.3,Y,BAPS,12.85,13,
...,3,2.25,Y,BAPS,-,-,
...," B 1-2",80,Y,MCKAY1,300,300,60

[axman6]

To add a little more detail, it seem to work correctly when the parsed type is a Maybe Text but not a Maybe Double