fs2000.mod: add mode_check plots and fix datatomfile command

See merge request Dynare/dynare!2064

load_results_after_load_mh: fix location of file

See merge request !2065

bug fixes in error traps in PKF update steps

See merge request Dynare/dynare!2063

Problem introduced in previous commit.

Ref. !2062

Bytecode MEX: fix bug with PowerDeriv printing introduced in ff85fc64

A move to fixed format was erroneously made in
4893f0e8 and
ff85fc64, where stream formatting of floating
points has been replaced by the use of std::to_string().

Bytecode MEX: split out code for dealing with variable names into a dedicated BasicSymbolTable class

Remnant of refactorization in 4445f17e

Ref. !2058

In particular, minimize the number of parentheses written, using the same
algorithm as in the preprocessor.

Ref. !2061

The logic for testing the MATLAB version was incorrect.

bug fix for smoother_redux and state uncertainty with OCCBIN

Closes #1862

See merge request Dynare/dynare!2060

Use an iterator wrapped inside std::optional instead of a possibly-singular
iterator, because the latter has undefined behaviour.

By the way, pass arguments by const reference.

The wrong type was used for querying symbol names.

Various fixes to smoother output

See merge request Dynare/dynare!2057

fix bug in ambiguity in the first regime stored, between 01 10 and 11.

See merge request Dynare/dynare!2055

Related to Dynare/dynare#1861

evaluate_planner_objective.m: fix output for linear-quadratic problems solved at second order

See merge request Dynare/dynare!2056

Related to Dynare/dynare#1861

Welfare does not correspond to the steady state in this case