This started out as a fix for '#H5460 - minor monster detection bug'
but that report turned out to be wrong. It claimed that pets weren't
highlighted as pets if the only way to observe them was via extended
monster detection, but the code (both 3.6.0 and current) indicates
otherwise. Detected monster highlighting is bypassed for pets.
Reorganize the code slightly to emphasize that this is intentional:
tameness trumps remote detection when choosing which highlight method.
For tty, if hilite_pet and use_inverse are both enabled or both
disabled, you can't see the difference anyway. At least I can't....
That report also wanted the use_inverse option to be changed (I guess
it's overloaded for multiple things) so I haven't marked #H5460 as
closed.