Add reset option to shocks-block
Currently the only way to set a different covariance matrix of structural shocks and measurement errors is to manually set all elements that differ from the previous shocks-statement. It would be nice to have something like
shocks(reset); var e; stderr 0.9; end;
that sets all elements of the M_.Sigma_e and M_.H to 0 before filling it again with the entries of the shocks-block.