Fixing GA code


git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@22987 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
IntersectPath[ <Plane>, <Polyhedron> ]

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@22990 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
IntersectPath[ <Line>, <Polygon> ] : merge following segments

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@22991 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Use constant Vz as main direction.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@22992 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e