Normann Rion authored Jun 15, 2021 and Sébastien Villemot committed Jun 15, 2021

Partially addresses issue #1680:
- unconditional welfare resorts to dynare++ simulation tools, which shall be updated very soon
TO DO:
- implement a function computing kth-order approximation of simulated moments of y

— Ondra Kamenik has agreed to the relicensing of utils and parser modules to
  GPL
— add DynareTeam’s copyright, since we have made a lot of modifications
— add proper copyright notices in all files

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- encapsulate it more clearly
- make it thread safe
- put back the Pascal triangle initialization stuff removed in 9512a32a

- TL_RAISE now unconditionally raises an exception
- rathe use TL_RAISE_IF at some places, to save a test in non-debug mode

Previously it was returning a pointer, which is non-standard for containers,
and was leading to ugly dereferencing everywhere.

We now use a initializer list constructor for creating symmetries of the form
$y^n$, $y^n u^m$, $y^nu^m\sigma^k$.

The constructor taking a single integer is used to initialize a symmetry of a
given length.

Similar changes are made to IntSequence.

This behavior is similar to std::vector.

On Windows, this means that a POSIX threads implementation is no longer needed,
since C++11 threads are implemented using native Windows threads.

On GNU/Linux and macOS, POSIX threads are still used under the hood.

A new m4 macro (AX_CXX11_THREAD) is used to add the proper compilation
flags (instead of AX_PTHREAD).

- these classes now encapsulate a std::shared_ptr<{const, }double>, so that
  they do not perform memory management, and several {Const,}Vector instances
  can transparently share the same underlying data

- make converting constructor from ConstVector to Vector explicit, since that
  entails memory allocation (but the reverse conversion is almost costless, so
  keep it implicit); do the same for GeneralMatrix/ConstGeneralMatrix,
  TwoDMatrix/ConstTwoDMatrix

- remove the constructors that were extracting a row/column from a matrix, and
  replace them by getRow() and getCol() methods on {Const,}GeneralMatrix

- rename and change the API of the complex version Vector::add(), so that it is
  explicit that it deals with complex numbers

- add constructors that take a MATLAB mxArray

Performed using modernize-use-using from clang-tidy.

https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-using.html

Performed using modernize-use-override from clang-tidy.

https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-override.html

Performed using modernize-use-equals-default from clang-tidy.

https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-equals-default.html

Performed using modernize-use-auto from clang-tidy.

https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-auto.html

By the way apply Dynare C++ coding style and extensions (.cc/.hh).