Fix for #4716

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37440 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Logout method in API

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37441 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e