Add option to set max HFR for the guide star selected by SEP MultiStar.

Main fix sets the maximum HFR for a guide star. Adds a control for this in the Guide options, under the Guide tab, see max hfr.

Testing: To test, you need to look in the log, and see the guide star's hfr. E.g. if you run in the simulator, set the max hfr to e.g. 2.0 and start guiding, and note that (assuming you have verbose file logging with guide checked) the table listing the selected guide star in the log shows an hfr no greater than 2.0. If you set it back to e.g. 4.5 which is the default, you should see a greater hfr guide star chosen.

Also fixes issue with analyze info box's background color.