Prevent type error in Data analysis view

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36401 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[web] image tool creates points

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36402 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
classes for Implicit Curve plotting - #4345

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36403 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
comments added

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36404 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e