Allow for expressions in _calibration-blocks

In statements like

irf_calibration(relative_irf);
y(1:4), e_ys, [0 10]; //[first year response, logical OR]
end;

we only allow for numbers. We should also allow e.g.

irf_calibration(relative_irf);
y(1:4), e_ys, [0 UB_1]; //[first year response, logical OR]
end;

where UB_1 is an interpretable expression like a parameter or a list element.