Preprocessor update

– Make preprocessor recognize default order=2 of stoch_simul
— Fix faulty logic in checks for mh_tune_jscale
— Fix handling of multiple PAC models
— PAC/MCE: improve informative message about # of aux. vars/eqs by adding the
  model name
— Fixes to include_eqs/exclude_eqs
— PAC model: rewrite the algorithm for detecting the target, to make it more
  robust
— PAC/MCE model: fix timing of target in PAC expectation term
— Add new “matched_moments” block

preprocessor @ c6ad212c

-Subproject commit d4e20c7ec4c31befc489ffcca945bc7916a30b3c
+Subproject commit c6ad212c8a068f68b12b161b7d0301c3ef1619a9