Ref dynare#1630

The idea is to make use of the dynamic_set_auxiliary_dseries.m file to generate
the initial conditions for all auxiliary variables, including the diffs.

Also remove the check done by the preprocessor for the lags in histval, since
it does not work correctly with the diff operator.

allow the use of previously assigned variables in epilogue block in later equations in epilogue block

- ExprNode::maxLag() and ExprNode::maxLead() now take into account exogenous
  deterministic variables, for consistency with M_.maximum_{lead,lag}

- ExprNode::maxLag() no longer behaves as if diff() operators were
  expanded (i.e. it now returns 1 on diff(x(-1))), for consistency with
  maxEndoLag() and maxExoLag()

- New ExprNode::maxLagWithDiffsExpanded() method, that behaves as maxLag() used
  to behave (except that it also takes exogenous deterministic into account)

Previously, this function was counting the total number of diff() operators in
an expression. But this is not very useful, and is potentially misleading,
because in practice we use this function to compute the maximum lag on
variables in levels.

This function now returns the maximum number of nested diffs.

For example, on diff(x)+diff(diff(y)), this function was returning 3, and it
now returns 2.

This was a bug, now fixed in Bison 3.2.2. The latter version is now available
on most platforms (Debian unstable/testing, Homebrew, MSYS2).

The data structure written in the driver file is changed also in the case of
the "variable" option.

Those const data members are simply made public.

The engine is now more robust and should reject any expression that does not
conform to the expected form. It is also able to deal with more cases, such as
terms appearing with a minus sign, or variables in the middle of a
three-factors product.

BTW, use a std::tuple for storing the result of the matching inside
PacExpectationNode, and change the order of components within the
structure (variable first, scalar last).

The preprocessor now writes all the symmetric elements in the "hp"
matrix (derivatives of the hessian w.r.t. parameters), for consistency with all
other derivatives output.

Previously it was only writing one of the two symmetric elements, when indices
of endogenous were different.

Also, no longer compute two times symmetric elements in derivation w.r.t.
parameters at order 2, for consistency with derivation w.r.t. endogenous.
It is therefore now necessary to duplicate them in the output to keep behavior
unchanged.

Thanks to Akim Demaille for the suggestion.

When creating the sparse matrix (in MATLAB or C mode), since storage is in
column-major order, output the first column, then the second, then the third.
This gives a significant performance boost in use_dll mode (at both compilation
and runtime), because it facilitates memory accesses and expression reusage.

Closes #13

This is the first step towards computing k-order derivatives.

Ref dynare#217, #10

This reverts commit 17dd4433.

This reverts commit 158f027d.

This reverts commit 3776e3b8.