Merge branch 'develop' into documentation

doc/buildsystem.rst

doc/html/_modules/index.html

doc/html/_modules/promod3/core/argcheck.html

doc/html/_sources/contributing.txt

doc/html/_static/basic.css

doc/html/_static/default.css

doc/html/_static/doctools.js

doc/html/_static/jquery.js

doc/html/_static/searchtools.js

doc/html/_static/sidebar.js

doc/html/_static/websupport.js

doc/html/buildsystem.html

doc/html/changelog.html

doc/html/contributing.html

doc/html/core/argcheck.html

doc/html/core/index.html

doc/html/developers.html

doc/html/genindex.html

doc/html/index.html

doc/html/meld/index.html