[giac] make sure that 3<x<5 syntax works to & from Giac

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25491 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
NPE fix

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25492 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e