Intersect[ ] shortcut for quadric/quadric (circle intersection), plane/polyhedron, plane/limited quadric

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24610 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] fix bug with Sample[{1,2,3,4},4, true]

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24611 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] updated unit tests

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24612 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] labeled GeoElements should not be expanded (copy Reduce code, change df to diff)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24613 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e