better initialization of kt, kr0, kr1, kr2 in optimize()
better initialization of kt, kr0, kr1, kr2 in optimize()

mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs