Make help clicks also work for UCI engines

Make help clicks also work for UCI engines

The help clicks were using the engine command to find the manual,
but this would not work for engines with parameters or using adapters.
Now it used the -fcp/scp arguments, and tidies these to stripp off
directory path and arguments. (cps->tidy could not be used, because
it is overwritten by the name reported by the engine itself, which
usually contains version numbers not in the manual name.)