[giac] serialize (r;t) to ((r)*cos(t), (r)*sin(t))

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25589 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
bugfix: mode not set in MyVecNode.deepCopy() -> (1;1) not working in CAS #3297

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25590 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e