Update


git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23500 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
preview is not updated when cursor is outside of any object

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23501 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Fixed NPE

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23502 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
general no-CAS derivative (part 1)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23503 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e