Modified behavior of reading parameter file.
Modified behavior of reading parameter file.

Previously, a parameter file appeared to be:
rownum colnum [neg]

rownum - Row of mm3.fld
colnum - Column of mm3.fld (1, 2, or 3. See __doc__ for more details
         on the meaning of these numbers)
neg    - Option string added as third column to restrict parameters
         to be negative.

Now, the 3rd column can be neg or pos. The keyword pos will restrict
the parameters to be positive. If left without a third column, the
code will decide itself whether to allow negative values.

Q2MM/q2mm,arosale4/q2mm,Q2MM/q2mm,arosale4/q2mm,ericchansen/q2mm,ericchansen/q2mm