null pointer fix

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35237 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
fix compile error (Linux!)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35238 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Polynomial class refactoring

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35239 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e