PLT command lengths in xspec v11

Bill ran into a problem running the Swift processing script under Hera. He needed to create a gif file in xspec v11 in a remote directory with a long pathname. This overran the string length available in xspec. Modified xspec to allow longer PLT command names and device names. I also had to modify PLT to increase the allowed device name length. The limit now is 80 characters which seems to be imposed by the PGPLOT code. I've not tried to track down where that is set.