Implement broadcasting for operations (+,-,* and /) between dseries and scalar or vectors. Efficiency and cosmetic changes.

2 additional commits

If there is any call to exist(fname) before the call to the preprocessor, then
Octave will use the old copy of the .m instead of the newly generated one.
Deleting the .m beforehand fixes the problem.

- no longer use OCTAVE_QUIT in MEX files; this seems now only possible in
  oct-files. (Ref #304)
- do not build linsolve.oct on Octave >= 3.8, it is available natively.
- do not add strjoin.m to the patch on Octave >= 3.8, it is available natively.
- default_save_options has been renamed save_default_options.

Changes in conditional forecast using the extended path

New syntax used to call the conditional forecast using the extended path method. It allows to match the endogenous and the shock that are flipped.

The previous syntax used to call the conditional forecast using the extended path method was problematic. It does not allow to match the endogenous and the shock that are flipped. This is problematic as soon as the forecast periods are heterogeneous or the type of expectation (surprise or perfect foresight) are different. We get rid of the previous syntax.

Shock decom documentation