R/MxExpectationGREML.R : repair backend data-column-check bug.
R/MxExpectationGREML.R : repair backend data-column-check bug.

Historical note: The frontend GREML expectation holds an MxData object, which
contains the phenotype vector y on one row, which the GREML fitfunction backend
uses.  At one point in mxGREML's development, it was necessary for the backend
to use the number of columns in that one-row y, which was represented as a
range of integers from 0 to the actual number of columns, stored in slot
'dataColumns'.  But now, the GREML backend does not use 'dataColumns', and the
backend expectation API has a sanity check on the data-types of the columns
of the MxModel's dataset, and that check needs 'dataColumns' to reference no
more than the actual number of columns in the dataset.  I am surprised the bug
this commit repairs went undiscovered for as long as it did.

jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx