Fixes incorrect horizontal and vertical end-point scaling of model's
saturation functions.
API Change: No longer supports user-selected behaviour for treating
scaled end-points with a sentinel value (-1.0E+20). That option was
introduced due to incomplete understanding of the semantics of the
sentinel value. Now that we understand the meaning (use actual,
unscaled end-point value from input table), we no longer need the
option. Update the calling code in RigFlowDiagSolverInterface.cpp
accordingly.
