used to kx.
(create_and_write_cookie): New function to generate and write into a
file a local cookie used between this pseudo-server and the clients on
this host.
(start_session): New function to check and remove the local cookie
before the data is sent over to `kx'.
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@732 ec53bebd-3082-4978-b11e-865c3cabbd6b