Should fix build error in travis-ci.

Packages are no longer autoloaded, so testing whether they are "Loaded" does
not work in all cases.

The function now ensures that the package is loaded.

This change was made for consistency with commit 7cbac0c9 in Dynare.

... Also do not crash dynare_config() if matlab is not able to download the X13 binary.

The input arguments (concatenated objects) should not be modified by
the overloaded method. Use a copy.

Created instead a new function dseries2struct, which can be called as:

>> o = dseries(randn(10,2));
>> s = o.struct();

Also

 + Added a routine to create a dseries object from a structure (if all
 required field are available).

 + Added the possibility to instantiate a dseries object from a structure.

Fixed problems in FORECAST output (option fvr)

All commands except series and composite.