[DynareDev] Updates for Windows users

Hi,

Recently, the MinGW packages for 32-bit and 64-bit have entered Cygwin.

This will facilitate the life of Windows users and developers of Dynare in two ways:

- the compilation of Dynare under Windows can now be entirely done under Cygwin, without the need to download an external compiler; the Windows section on the wiki page has been correspondingly updated: http://www.dynare.org/DynareWiki/BuildingDynareFromSource

- the "use_dll" option also benefits from this change, and in particular it is possible to use GCC under 64-bit MATLAB with this option. An updated "mexopts.bat" file, using the new MinGW packages, is available on the following page: http://www.dynare.org/DynareWiki/ConfigureMatlabWindowsForMexCompilation

Best,