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.