Turn nat off before each CAS call. This should make sure it is not randomly enabled in Web.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23513 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
general no-CAS derivative (part 2)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23514 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e