Preprocessor update

— Properly escape some characters in JSON. As a consequence, remove the
  workaround that was in matlab/loadjson_.m
— Fix JSON output for load_params_and_steady_state
— Add maximum lead/lag and varobs to JSON output

matlab/loadjson_.m

@@ -13,7 +13,7 @@ function o = loadjson_(jsonfilename)
 % available under Octave. Old Matlab versions and Octave use
 % jsonlab as fallback. 
 
-% Copyright (C) 2020 Dynare Team
+% Copyright (C) 2020-2021 Dynare Team
 %
 % This file is part of Dynare.
 %
@@ -37,10 +37,5 @@ end
 
 json = fileread(jsonfilename);
 
-% Remove some escape characters that cannot be interpreted by jsondecode
-json = strrep(json, '\w', '\\w');
-json = strrep(json, '\_', '\\_');
-json = strrep(json, '\\\_', '\\_');
-
 o = jsondecode(json); clear('json');
-o = convertjsondecode(o);
+o = convertjsondecode(o);
\ No newline at end of file

preprocessor @ e3c716fa

-Subproject commit 29b3b744ef01b30118daa9568fe0e8adaa86ef1b
+Subproject commit e3c716faba552bb59146b3b83d6c2fef5e650299