Adaptive grid distance for planes (corresponding to x-axis inter-ticks)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30343 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Update grid geometry for planes only if visible

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30344 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Intersection curves : fix default value for zNear

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30345 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e