Method of Moments: Add GMM analytical standard errors and some other minor fixes
This MR adds the ability to compute standard errors analytically for GMM at orders 1,2 and 3. It is based on the analytical Parameter Jacobian of moments for which we already have functions for that we use in the identification toolbox.
This MR also adds some additional fixes and checks for the perturbation order and pruning.
Lastly, it updates the To-Do list (see also the commit messages for more information).
Edited by Johannes Pfeifer