[giac] improve output of Conic.5 (remove common factor)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26571 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
revert mistake in previous commit

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26572 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] add Vector.2

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26573 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e