Moved isweekly, ismonthly, isquaterly and isyearly routines from matlab/@dynSeries/private to matlab/utilities/dates. Adapted dynare_config conformably to these changes.

Compute tensorial grid (based on a univariate gauss hermite quadrature) for future shocks by default.

Cosmetic change. Redifinition of the nodes (removed the division by the square root of two) so that the routine is specialized for the integration of functions with gaussian weights.

Added routine computing Gaussian cubature weights and nodes (implementation of algorithms described in Stroud 1971).

2) also impose a sequence of univariate steps in the first iteration;

Replace them by equivalents in M_ (and an extra one: M_.dynamic).

IMPORTANT POINT: oo_.dr.npred used to count both purely backward and mixed/both
variables. This was the cause of lots of confusion. The new M_.npred only
counts purely backward variables.

We now have the following indentities:

M_.npred + M_.nboth + M_.nfwrd + M_.nstatic = M_.endo_nbr
M_.nspred = M_.npred + M_.nboth
M_.nsfwrd = M_.nfwrd + M_.nboth
M_.ndynamic = M_.npred + M_.nboth + M_.nfwrd