Use ReplaceShorterLiterals option to enforce replacement of all strings.

https://clang.llvm.org/extra/clang-tidy/checks/modernize-raw-string-literal.html

By the way, fix bug in detection of duplicate elements.

This is more elegant, and makes it easier to distinguish them from integer
options.

Ref dynare#1648

This reverts commit 21d42e60.

Add in M_ a list of exogenous variables that needs to be excluded if the model is not used for estimation.

Here, emplace() and insert() are not interchangeable because this is a std::set of
std::vector<int>, and we really want the initializer-list constructor of
std::vector (and not the two int's constructor).

Fixes the test deterministic_simulations/lola_solve_one_boundary.mod

In particular, no need to put both upper and lower case letters in the
patterns, since the lexer is case-insensitive.

The only simplification that we do not perform is removing the quoting of
single quotes (i.e. replacing \' by '), since it confuses the C++ mode of
Emacs.