Indexes all C++, Fortran and C files (including submodules).

Also add a dependency of dr.pdf on dr.bib.

[skip ci]

Incidentally, no longer run Dynare++ unit tests, since they are intricated in
the Dynare++ build system. If we finally decide not to drop the Dynare++
codebase for our MEX files, then we should probably find a way to build and run
them again.

Ref. #1825

– preprocessor binary renamed to dynare-preprocessor
— the preprocessor binary is now installed under a preprocessor/ top-level directory
— a backward-compatibility symlink is still provided under
  matlab/preprocessor64/dynare_m
— the make install rule now install PDF and HTML documentation when those have
  been built

Closes: #1728

By the same token, remove unused support for Fortran 77.

I’m not sure it has ever worked.

As a consequence, remove the workaround that had apparently been implemented in
tests/initval_file/ramst_initval_file.mod.

This MEX solves nonlinear systems of equations using a trust region algorithm.
The problem is subdivided in smaller problems by doing a block
triangularisation of the Jacobian at the guess value, using the
Dulmage-Mendelsohn algorithm.

The interface of the MEX is simply:

  [x, info] = block_trust_region(f, guess_value);

Where f is either a function handle or a string designating a function.
f must take one argument (the evaluation point), and return either one or two
arguments (the residuals and, optionally, the Jacobian).

On success, info=0; on failure, info=1.

By the same token, remove unused support for Fortran 77.

Those archives contain 3 hidden files, which always have the same name. This
can make the parallel build fail when several packages are unpacked at the same
time. Hence, we just skip these files when unpacking.

This makes the testsuite robust to network failures.

We only need to recompile Slicot and x13as.

The scripts are based the former “dynare-build” project. They have been
overhauled and simplified.

Building a Windows package (both installer and zip archive) is as easy as
running “make -C windows” (provided the right Debian packages are installed,
use the “windows/install-packages.sh” script for that purpose).

The layout of MEX files for Octave in the package has been
changed (mex/octave/win32/ and mex/octave/win64/ instead of mex/octave32/ and
mex/octave/), for consistency with MATLAB MEX.

We now use a symbolic link farm to make source file accessible from build
directories.

Closes #466

- integrate with autoconf/automake, so that "make html pdf" now build the
  manual
- remove the old texinfo manual
- the PDF manual is now called dynare-manual.pdf (Closes #1543)
- add a Gitlab CI job that updates the online unstable manual under
  www.dynare.org/manual-unstable/

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

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

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