Auto create sliders - half way (#3490)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@31619 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Auto create sliders dialog - message text. (#3490)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@31620 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#3985 Preview fix

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@31621 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e