Integrate DMM

http://ipsc.jrc.ec.europa.eu/?id=790 http://ipsc.jrc.ec.europa.eu/fileadmin/repository/sfa/finepro/software/DMMmanual.pdf

removed milestone

@rattoma Is this still current? The links above are dead and https://ec.europa.eu/jrc/en/macro-econometric-statistical-software/econometric-software does not mention DMM despite https://ec.europa.eu/jrc/en/scientific-tool/econometric-statistical-software-packages saying it should.

marked this issue as related to #642

marked this issue as related to #226

The files are currently already shipped (999cbdc9), but they are not integrated.

closed with commit d41306f0

mentioned in commit 7cf9411e